SEO (search engine optimisation) can be full of jargon, abbreviations, and technical terminology.
We thought it would be useful to put together a fresh SEO glossary updated for 2021.
We will make sure to adjust the 'last updated' date at the end of glossary every time we make a update. SEO best practice changes and evolves - something a good glossary should reflect.
This glossary has been produced by multiple experienced SEO experts and has been peer reviewed for errors. If you have a contribution or suggestion feel free to tweet us @SearchCandy or get in contact.
You can browse the glossary alphabetically using the index below or using full topic index in the sidebar.
Above the fold
Above the fold refers to the upper area of a webpage that is visible without a user having to scroll down.
Accelerated Mobile Pages (AMP)
The Accelerated Mobile Pages Project is a Google initiative to build fast loading pages for mobile users. So called 'AMP' pages are designed to load quickly, whilst still including rich content such as videos, animations and ads. The pages are powered by the AMP HTML framework.
Google AdWords is Google's Pay Per Click online marketing platform, first launched in the year 2000. Users can buy advertising across the Google network of web properties and also on other third party websites via the Google Display Network.
Founded in 2011 by Dmitry Gerasimenko, Ahrefs is an SaaS SEO platform most popular for its backlink discovery tool Site Explorer.
Algorithm, sometimes shortened to 'algo', refers to a set of rules that a computer program, or in this case a search engine, uses to make calculations or fulfill a task. It is most frequently used in relation to Google's algorithms. The PageRank algorithm is one of the most famous examples of a Google algorithm.
Alphabet - full name: Alphabet Inc. - is Google's new holding company as of August 2015. Based in California, the company has Google's co-founders Larry Page as CEO and Sergey Brin as President. The largest subsidary of Alphabet is Google Inc., and is also the parent company of other ventures including Google Capital, X, Calico, GV, Google Fiber, Jigsaw, Nest Labs, Sidewalk Labs, and Verily.
Alt text (alternative text) is a word or phrase that can be added to an image element in HTML, used to describe the image to users and search engines. Eg:
<img src="/dictionary.jpg" alt="Dictionary" />
Authority in terms of SEO refers to the authority of a website, which is measured by a variety of metrics and different services. A website that has attributes such as good rankings, strong backlinks and popularity, would be considered to have a high authority.
An authority site is a particularly high quality website. An authority site could technically be a commercial website that is the authority on a topic, though for many SEOs in certain contexts (ie for the purposes of writing an article) an authority site is generally considered to be either governmental, an association, or otherwise neutral from a commercial perspective.
Backlinks are links from one site to another. The acquisition of backlinks is usually a standard part of a full SEO campaign.
Barry Schwartz is an SEO industry veteran and owner of Search Engine Roundtable and Rusty Brick. SERoundTable is a great place to learn more about SEO and keep up to date with Google updates.
BERT is a method of natural language processing (NLP) pre-training named 'Bidirectional Encoder Representations from Transformers' - aka BERT. In October 2019 Google announced that they were using BERT in Google Search.
Black hat (also see: White hat, Grey hat) refers to an SEO or technique that that is more aggressive in nature. Blackhat SEOs frequently use combinations of (among other techniques) spam link acquisition and bulk site creation methods to try to rank highly in the search engine results.
Blogger outreach is the process of contacting and working with bloggers as part of a marketing campaign.
Using boolean search operators it is possible to connect search words together to broaden or narrow a set of results. The three basic boolean operators are
NOT. By default however search engines will usually apply
AND for each part of a query unless specified otherwise.
A bot (alternately spider, crawler,) is a software application that runs automated tasks over the internet. Google's main bot for web crawling is Googlebot.
Bounce rate refers to the percentage of users that view one page then leave a website. For example if 8 in every 10 users leave a website after viewing one page then there is said to be an 80% bounce rate.
In terms of anchor text, a branded link is a link which contains to company brand or similar derivative in the anchor text. Example branded link for Search Candy would be "Search Candy", "SearchCandy" and "SearchCandy.uk".
BrightonSEO is the biggest SEO conference in the UK by a long way. Founded by Kelvin Newman, conference tickets are known to sell out in minutes.
A broken link is a link to a URL that is not working correctly. If a user were to click the link it would lead to a 404 page or other type of error page in the browser.
rel="canonical" link element can be used to specify the canonical URL of a webpage.
The canonical URL is the preferred URL a webmaster wishes to display for a particular webpage, and can be used to rectify a variety of canonicalisation and duplicate content related issues.
Citation (Local SEO)
When looking at local SEO, a citation is usually seen as a reference to the name, address and phone number (NAP) of a business.
Click Through Rate (CTR)
Click Through Rate (CTR) is the rate, usually expressed as a percentage, at which users click an ad in PPC, or a link in a result set in SEO.
Cloak / Cloaking
Cloaking is the black hat (and not recommended) practice of serving different content to Google than as seen by users. It is a technique that is generally still used only by spammers and those with malicious intent.
Content Delivery Network (CDN)
A Content Delivery Network, usually shortened to CDN, is a distributed network of hosting locations that serve HTML or static resources based on user geo-location.
Content marketing involves the creation and distribution of content as part of a marketing strategy, usually designed to attract new customers.
Conversion Rate Optimisation (CRO)
Conversion Rate Optimisation, usually shorted to CRO, is the practice of optimising the user experience of websites and landing pages to achieve the most goals/revenue.
Core Updates (or ‘Broad Core Updates’) are Google algorithm updates which are more significant than other smaller incremental updates. Google says Core Updates should be more ‘noticeable’, and made only ‘several times a year’. Core Updates should usually be announced by Google via communication channels such as Twitter or the Official Webmaster Central blog.
Core Web Vitals
Core Web Vitals (or ‘Web Vitals’) are a set of page experience metrics created by Google which have now been built into the algorithm as a ranking factor, combined with existing signals such as page speed and mobile friendliness. The primary metrics that make up Core Web Vitals are Largest Contentful Paint, First Input Delay, and Cumulative Layout Shift.
Crawl / Crawling
Crawling is the process by which a bot visits a website. In the search engine indexing process, crawling is when a search engine bot (such as Googlebot), visits a web resource in order to view, parse, and then if required index the resource.
Crawl errors are errors that occur during the crawling process by a search engine bot or other crawler. Errors could include DNS errors, server connectivity issues, or errors caused by the unavailability of a resource such as the Robots.txt file.
Danny Sullivan is a veteran of the SEO industry, working as a journalist, CCO of Third Door Media and co-founder Search Engine Land. In October 2017 Danny announced he was joining Google working as a public liaison of search, running the Twitter account @searchliaison.
De-index / De-indexing
A resource that has been de-indexed has been temporarily or permanently removed from search engine results. the resource is no longer in the search engine index.
Disavowing links is the process of telling Google that you do not want the links to count towards your site. For example if you feel that the links are spammy, or that they had been purchased as part of a previous SEO campaign and you need to now tidy them up. You can disavow links via the Disavow tool in Search Console.
The Disavow tool is Google's tool for disavowing links. Webmasters can upload a file containing URLs/domains to disavow. You can find the tool here.
Domain Authority (DA)
Domain Authority is a metric created by Moz, which on a 100 point scale is designed to reflect how well a domain will rank in search engines. A higher score represents a higher domain authority.
A doorway page is a resource that is designed to attract SEO traffic but which usually contains little real value to users.
A do-follow link (or 'follow link') is a link which has not had the Nofollow rel attribute applied to it. This means generally speaking that it is a link which passes PageRank. 'Do-follow' is not a value or attribute that is used in the code itself.
Duplicate content is text based content which appears in more than one location, or replicates partially or fully content that already exists elsewhere on the web.
SEO that is focused on increasing traffic and sales for e-commerce related websites that sell products online.
Expertise, Authoritativeness, Trustworthiness (EAT)
EAT, which is an acronym for 'Expertise, Authoritativeness, Trustworthiness', is a metric by which Google's Quality Raters assess webpages.
An external link is a link that points to a different website than the link is found on. For example a link from
Featured Snippets are special boxes shown at the top of search results in Google which can contain short pieces of text and images. Since June 2020 these snippets now automatically make use of Scroll to Text Fragment links.
Fetch as Google (Fetch as Googlebot)
Firebase is a Google owned mobile platform that offers a range of services for mobile app developers.
Google Analytics is a web analytics tool available at both a freemium and premium level by Google. Users can track information about visitors, including data on pages viewed and much more.
The process of multiple web users trying to change Google's search rankings, often for comic (though sometimes malicious) effect.
Google Bowling refers broadly to negative SEO: the practice of trying to maliciously affect the results of a website or competitor.
Google's search engine results change frequently, and more so in the past when rankings and algorithms changed less frequently, this shuffling of results became known as the Google Dance.
Introduced in 2018, Google Discover is the new and updated Google Feed, a personalised feed of news and information for users of the Google app for Android or iOS, and all mobile browsers visiting the Google homepage.
Google Jobs Search
Google's Job Search system allows recruitment companies and aggregators to post jobs direct to Google using the Job Posting schema.
Google I/O is Google's annual developer conference focusing on technologies such as Android, Chrome, Chrome OS, APIs and more. The I and O in the name of the conference stands for 'input' and 'output'.
Google News Sitemap
A Google News Sitemap is a sitemap used to assist Google in the indexing of Google News specific content. A Google News Sitemap should only contain resources that adhere to the various Google News guidelines.
Google Posts is a limited new social service from Google. It is described by Google as "Your Podium On Google Search".
Google Webmaster Guidelines
The Google Webmaster Guidelines are a set of suggestions and rules from Google that webmasters should follow to ensure websites are indexed optimally.
Google Webmaster Tools
Google Webmaster Tools is the old name for the Google Search Console.
Googlebot is Google's primary bot that is used to crawl web pages.
Grey hat SEO is the practice of SEO techniques that fall between white hat and black hat SEO. Much of SEO conducted could arguably be said to fall within the area of greyhat SEO.
Growth Hacking is the practice of using data/analytical driven and viral marketing techniques to generate sales and exposure.
The front page of a website. Usually found at the root of a domain, eg
Heading Tags / Elements (H1, H2, H3, H4, H5, H6)
The heading element in HTML defines a structure for headings in a document. Starting with H1 as the most important heading, descending to H6, heading tags have been a standard part of HTML since HTML 2.0.
Hits are visitors to a website. A successful campaign could be said to be one which delivered a lot of hits. Hits are not necessarily specific to a particular platform, they could be search engine visits, PPC, social media, or from people clicking a link on another website.
The hreflang attributes can be used to ensure the correct language and regional websites are served in search results. The Hreflang specification can be applied using the
hreflang="x" attributes with the applicable language code inside a link element, via a HTTP header or a sitemap. Read our guide to the Hreflang specification here.
Hummingbird is a Google search algorithm, first announced August 2013. Hummingbird was aimed at understanding the concepts behind keywords.
H1 Tag / Element
The H1 tag is the most important heading element on a web resource. Generally there should only be one H1 on a page, but it is not a major problem to use more than one if it helps to describe the content of a page, if there are for example there is more than one section on a page.
An image sitemap is an XML sitemap file that is designed to show to a search engine the images used on a website.
An inbound link is a link that comes from another website.
Index / Indexing
Index (noun) & Indexing (verb) in SEO can refer to various processes related to being crawled and then stored in a search engine's database. A webmaster that is having indexing issues is having problems at some stage that is causing a resource or resources not be found (indexed) in a search engine.
An internal link is a link that points to a resource found on the same website that the link is found on. For example a link from
SEOs usually work either at a marketing agency, in-house for an organisation, freelance, part-time, are self-employed, or own a company. SEO job titles include: SEO executive, blogger outreach, link building, content marketing, technical SEO, campaign manager, account manager, SEO manager, Head of SEO, and executive level positions.
John Mueller aka John Mu is Webmaster Trends Analyst at Google, and a very active figure in the webmaster community.
From an SEO perspective a keyword is a word (or phrase) from which people might find a website when used as a query in Google.
Keyword density refers to the amount of times a certain keyword has been used in a body of text, expressed as a percentage. Generally there is no 'perfect' keyword density that you should aim for.
The Google Keyword Planner is a service for finding keyword ideas that is part of Google AdWords.
Keyword research is the process by which SEOs try to find the words and phrases that potential customers might search for to find a resource.
Knowledge carousels, alternatively known as knowledge graph carousels, display lists of knowledge graph entities in a carousel format at the top of Google results.
The Knowledge Graph is a knowledge base system created and set of new richer features from Google first announced in May 2012. Knowledge Graph results provide structured and detailed information about topics.
The Knowledge Vault is a knowledge base project by Google that encompasses over 1.6 billion facts that have been collected from the internet.
A link (also see backlink) is a hyper-link that when clicked will take a user from one resource or area of a page to another.
Link bait is a piece of content or action that is undertaken for the purpose of gaining links. An example of a piece of link bait might be an incendiary blog-post on a topic.
Link building is the process of building links to a website or resource. Link building is a key part of most full SEO campaigns and is undertaken for the purpose of increasing the authority of a resource.
Link equity is a concept that generally refers to the links has acquired via followed links or 301 redirected websites.
A link exchange is a relatively outdated and ill-advised method of acquiring backlinks, in which two people exchange links in some form.
SEO that is aimed at local and regional listings in search engines.
A manual penalty is a manual action taken against a website found to be breaking the Google webmaster guidelines, as determined by a human reviewer at Google.
Matt Cutts was previously Head of Google's Webspam Team.
The meta description is an attribute that describes the content of the webpage to search engines. The meta description may then be implemented in the snippet shown in search engine results.
Meta keywords are a now relatively outdated but still widely used way of indicating to search engines keywords that describe the content of a webpage. Meta keywords are not used by Google, but may be still be used by some search engines around the world.
Mobile first indexing
In November 2016 Google announced that they were experimenting with a mobile first index, meaning a stronger focus on mobile sites in algorithmic calculations. In March 2018 Google announced they were migrating some sites that followed best practice to mobile first indexing.
Mobile usability report
The Google Mobile usability report tool shows a count of mobile usability errors for a domain in Search Console.
Moz (formerly SEOmoz) is an SEO focused SaaS platform and website aimed at SEOs and small business owners.
Negative SEO (also see Google Bowling) is the practice maliciously trying to alter the search engine results of a website or competitor.
The Noarchive value when used in a Robots meta tag or similar method, instructs Google and other search engines not to store a cached archive copy of a resource.
Nofollow is a value that can be assigned to the rel attribute in HTML, for the purpose of not passing on SEO value. No follow links are now the standard when it comes to comment links for example.
To 'noindex' a resource is to issue an instruction to search engines not to index (include) the resource in search engine results. Noindex is a value that can be applied to the Robots meta tag, or via another method such as using the X-Robots-Tag HTTP header.
Noopener is a value that can be assigned to the rel attribute in a link to protect against reverse tabnabbing. It does not have an impact on SEO in a link that it is added to.
Noreferrer is a value that can be assigned to the rel attribute which tells the browser not to leak any HTTP refferer information, and is used in conjunction with noopener to protect against reverse tabnabbing. It does not have an impact on SEO in a link that it is added to.
Open Graph Protocol / Open Graph META Tags
The Open Graph Protocol is a structured data platform created by Facebook. Using Open Graph Meta tags such as
og:image it is possible to provide information about a resource to Facebook and other platforms.
Organic traffic is genuine web traffic (users/visitors to a web resource) that originates from non-paid search engine queries. Ie. visits from search engines that did not come from AdWords or other paid search engine distribution channels.
PageRank is a computer algorithm used by Google as part of their ranking systems. Developed in 1996, PageRank is named after Larry Page, one of the Google co-founders.
Page Authority (PA)
Page Authority is a metric created by Moz, which on a 100 point scale that attempts to reflect how well a specific page/URL will rank in search engines. A higher score represents a higher Page Authority.
Google Panda is a series of changes to Google's algorithm for ranking websites aimed at improving results, named after the engineer Navneet Panda. Panda is often considered to be a content focused algorithm.
Pay Per Click (PPC)
Pay per click, usually shortened to the acronym PPC, is a marketing model whereby adverts are shown to users with the aim of delivering traffic to a resource. Advertisers are charged simply speaking on the basis of how many times users click the adverts and visit the resource. Google's PPC marketing platform Adwords is the current market leader in much of the world.
Google Penguin is a series of algorithm updates designed to improve Google results. Penguin is considered to be an update that focuses on link related metrics.
Pigeon is the name given to a Google algorithm launched in July 2014 that was aimed at improving local search.
The preferred domain refers to the domain (www vs non-www) which a webmaster would like Google to use in search engine results pages.
Private Blog Network (PBN)
A Private Blog Network, usually shorted to PBN, is a network of blogs created for SEO/link purposes.
A query is a request for information from a database or service. In SEO it refers more specifically to the query that a user makes to a search engine.
RankBrain is a machine learning artificial intelligence project announced to be in use by Google in October 2015.
Rankings as they are known in SEO refers to the position(s) of a website in the Google - or another provider's - search engine results pages (SERPs).
Reputation management (online/SEO)
Online reputation management looks at the search engine results for certain keywords - usually for name or brand based queries - and often for the purpose of removing or pushing down negative results, or otherwise ensuring a good results set.
Rich cards are a new type of mobile-optimised search result format developed from rich snippets.
Rich Results Test Tool
A tool released by Google in January 2019 allows users to preview how rich results will be shown in search results and edit code.
Robots.txt (robots exclusion standard)
The Robots.txt file is used as a communication method to control indexing from search engine bots. It is possible to allow and disallow all or specific search engines on areas of a website.
Robots Meta Tag
The Robots meta tag can contain one or more comma separated values which instruct search engines as to how a resource should be indexed and/or its links crawled. Possible values include
Index, Follow is the default value so does not need to be expressed.
ROI (Return On Investment)
ROI, short for Return On Investment, refers to the benefit that can be received from a service or action.
The root domain of a website is the shortest possible formation of a domain name/URL, not including a subdomain. For example
website.com is the root domain of
The 'Google Sandbox' is an algorithm that has allegedly existed since 2004, a filter that potentially affects new websites and/or links.
The Screaming Frog SEO Spider is a well respected SEO tool designed to help crawl websites and discover SEO issues. Screaming Frog was founded in 2010 and is made in the UK.
Google Search Console (previously Google Webmaster Tools) is the search engine's main webmaster portal. Search Console allows users to register websites with Google, adjust settings, submit sitemaps, and use a variety of site maintenance related tools such as Fetch as Google.
Search engine friendly (SEF) URLs
URLs which are seen as friendly to search engines - specifically looking at the characters and symbols that come after the domain name. Namely URLs which have characteristics such as being clean of unnecessary information and descriptive as to topic of the page.
Using search operators it is possible to possible to refine search results and access other search engine features. Operators include words such as
info:, as well as punctuation such as the minus symbol (
-). The official list of Google search operators can be found here.
How visible a website is in the search engine results for different keywords. A website with a high search visibility can be found in high positions for multiple keywords and queries.
SEO (Search Engine Optimisation)
Search Engine Optimisation, usually referred to by the acronym SEO, is the process of using optimisation techniques to help a website or resource to rank properly in search engines, with the ultimate aim of delivering an increased amount of organic traffic, leads and customers.
SERPs (Search Engine Results Pages)
SERPs, short for Search Engine Results Pages, are the search engine results for a particular keyword search.
A sitemap allows webmasters to submit to search engines a list of crawlable resources for indexing.
Static / HTML Sitemap
A static or HTML sitemap, is a user view-able HTML sitemap that links to resources that can be viewed by users and also crawled by a search engine for indexing.
Using structured data markup it is possible to annotate content so that it can be understood by Google and other web applications. With structured data it is possible to get rich snippet results in Google for your web pages, and for the data to be included in the Knowledge Graph.
A subdomain is a domain that is part of the main domain. The For example
anothersubdomain.example.com are a both subdomains of
Technical SEO is the practice of optimising the technical aspects of a website and server to perform better for SEO. Technical SEO looks at aspects like crawling, indexing, canonicalisation, internal linking, and server-side issues.
The title tag (
<title>) is used to indicate the title of a webpage to search engines. The title tag is one of the most important SEO related elements on the page, and may be implemented by Google and other search engines as the main title in a search engine result snippet.
Topical Trust Flow
Topical Trust Flow is a metric from Majestic that looks at the categorization of links pointing to a website or URL.
Trust Flow (TF)
Trust Flow is a metric created by Majestic that is designed to reflect on a 100 point scale the quantity and trustworthiness of links that are pointing to a website or URL. A higher score represents a site that appears to have more trustworthy and less questionable links. To calculate the ranking Majestic look at a range of seed sites and work on a process they call Majestic Trust Flow.
Unique content is a term used in SEO to mean text based content that is original and has not been used before. If a webpage is said to be lacking in unique content, it means that it has little content that is unique to that particular page.
A vertical or niche is a specific target market or area of operation in internet marketing.
Website load speed refers to how quickly a webpage loads for users. In 2010 Google announced that website load speed is now an official ranking factor.
White hat SEO is the practice of SEO methods that are intended to stay within the Google Webmaster Guidelines.
In terms of websites, widgets are usually simple dynamic apps that can be aped to websites. Links included in widgets are subject to the Google Webmaster Guidelines.
X (Google X)
X (previously known as Google X) is a research and development subsidiary of Alphabet.
An XML sitemap is an
.xml file that contains a sitemap/list of resources for search engines to crawl and index.
X-Robots-Tag HTTP header
Yoast is run by Joost de Valk, developer of various plugins such as the Yoast SEO WordPress plugin.
Your Money or Your Life (YMYL)
'Your Money or Your Life' (YMYL) is a phrase used in Google's Quality Raters' Handbook, which refers to pages where PQ (Page Quality) is particularly important - because they have "an impact on your current or future well-being (physical, financial, safety, etc.)".
HTTP Status Codes
200 OK is a server response code that represents a successful load of the webpage. This is the standard HTTP status response.
301 Moved Permanently
301 Moved Permanently is a server response code used for permanent redirection. In SEO it is frequently requested as it is the ideal type of redirect for situations such as if a URL changes.
302 Found is a response code used for temporary redirection. It tends to be used less frequently than a 301, and is only used in situations where a redirect is known to be temporary.
307 Temporary Redirect
A 307 Temporary Redirect HTTP status response code is shown in browsers when a site has HSTS (HTTP Strict Transport Security) in use. The 307 HTTP status is confirmation that HSTS is working correctly - users do not actually 307 redirect in the same way as a normal redirect. Similarly, Googlebot does not see or follow 307 redirects - instead following the actual HTTP to HTTPS redirect that should be in place as part of the HSTS specification.
308 Permanent Redirect
A 308 Permanent Redirect is a server HTTP response code used (quite rarely) for permanent redirection. A 308 HTTP response is near identical to a 301, and has been confirmed to be treated as such by Google.
404 Not Found
404 Not Found is a response that a resource cannot be found at this time. The resource may still be available in the future.
410 Gone is suitable for when a resource is no longer available, and will not be made available again in the future. This is used in situations where a resource is permanently removed, such as a product that will never be in stock again.
451 Unavailable For Legal Reasons
The 451 Unavailable For Legal Reasons HTTP status code can be used for situations where a resource must be blocked for legal reasons.
500 Internal Server Error
500 Internal Server Error is a generic error message that means there was a problem that prevented the web page from loading.