Reference
SEO Glossary
Clear, factual definitions for 50 essential SEO terms — from keyword density to Core Web Vitals, E-E-A-T to link juice. No jargon, no fluff.
On-Page SEO
15 termsKeyword DensityThe percentage of times a target keyword appears relative to the total word count on a page.Read definition →Meta DescriptionAn HTML attribute that summarises a page's content and appears as the snippet beneath the title in search results.Read definition →Title TagThe HTML <title> element that defines the clickable headline shown for a page in search engine results.Read definition →H1 TagThe primary HTML heading element on a page, signalling to search engines and users what the main topic is.Read definition →Canonical URLThe preferred URL for a page, declared via a rel="canonical" tag to prevent duplicate content issues.Read definition →Internal LinkingHyperlinks that connect one page on a website to another page on the same domain, distributing authority and aiding crawling.Read definition →Anchor TextThe visible, clickable text of a hyperlink that signals to search engines what the linked page is about.Read definition →Alt TextThe alternative text attribute on an HTML image tag that describes the image for search engines and screen readers.Read definition →Keyword StuffingThe black-hat practice of overloading a page with keywords in an unnatural way to manipulate search rankings.Read definition →LSI KeywordsSemantically related terms and synonyms that help search engines understand a page's full topical context.Read definition →E-E-A-TExperience, Expertise, Authoritativeness, and Trustworthiness — the four quality dimensions Google's raters use to evaluate content.Read definition →Search IntentThe underlying goal or purpose behind a search query — informational, navigational, commercial, or transactional.Read definition →Featured SnippetA selected search result displayed at the top of Google SERPs in a special highlighted box, also called "Position Zero."Read definition →Page Title (SEO)The combination of the title tag and on-page H1 that together define how search engines and users understand a page's topic.Read definition →Meta Robots TagAn HTML directive that controls whether search engines can index a page and follow its links.Read definition →
Technical SEO
12 termsRobots.txtA plain-text file at the root of a website that tells crawlers which URLs they are allowed or disallowed from accessing.Read definition →XML SitemapA structured XML file listing all important URLs on a website to help search engines discover and prioritise them for crawling.Read definition →Crawl BudgetThe number of pages Googlebot will crawl on a site within a given time period, determined by crawl rate and crawl demand.Read definition →Core Web VitalsGoogle's set of real-world performance metrics — LCP, INP, and CLS — that measure page loading, interactivity, and visual stability.Read definition →Page SpeedHow quickly a web page loads and becomes usable for a visitor, a factor in both user experience and search engine rankings.Read definition →HTTPSHyperText Transfer Protocol Secure — the encrypted version of HTTP that protects data in transit and is a Google ranking signal.Read definition →Structured DataStandardised code markup (typically JSON-LD) added to pages to help search engines understand content and enable rich results.Read definition →Schema MarkupVocabulary from schema.org that labels content types and properties so search engines can generate rich results.Read definition →hreflangAn HTML attribute that tells search engines which language and regional version of a page to serve to users in specific locales.Read definition →Redirect ChainA sequence of multiple redirects between the original URL and the final destination, which wastes crawl budget and dilutes link equity.Read definition →301 RedirectA permanent HTTP redirect that transfers users and link equity from one URL to another, signalling the change to search engines.Read definition →NoindexA directive that tells search engines not to include a page in their search index, removing it from search results.Read definition →
Content
8 termsReadability ScoreA numerical measure of how easy a piece of text is to read, calculated using formulas based on sentence and word complexity.Read definition →Flesch-KincaidA pair of widely used readability formulas — Reading Ease (0–100 score) and Grade Level — developed for the U.S. Navy in 1975.Read definition →Content GapTopics, keywords, or subtopics that competitors rank for but your site does not, representing missed traffic opportunities.Read definition →TF-IDFTerm Frequency–Inverse Document Frequency, a statistical measure that identifies the most significant terms in a document relative to a corpus.Read definition →Word CountThe total number of words in a piece of content, used as a proxy for content depth and coverage.Read definition →Duplicate ContentBlocks of content that are identical or substantially similar across multiple URLs, which can cause indexing and ranking dilution.Read definition →Thin ContentPages that provide little or no unique value to users — low word count, auto-generated text, or shallow coverage of a topic.Read definition →Content FreshnessHow recently content was created or updated, a ranking factor for time-sensitive queries where recency is part of user intent.Read definition →
Analytics
5 termsBounce RateThe percentage of sessions in which a user leaves a site after viewing only one page without any interaction.Read definition →Click-Through Rate (CTR)The percentage of users who click on a search result after seeing it in the SERP, calculated as clicks divided by impressions.Read definition →ImpressionsThe number of times a URL appeared in Google Search results for a query, regardless of whether it was clicked.Read definition →Organic TrafficWebsite visitors who arrive through unpaid search engine results, as distinguished from paid, direct, referral, or social traffic.Read definition →Dwell TimeThe length of time a user spends on a page after clicking from the SERP before returning to the search results.Read definition →
Links
6 termsBacklinkA hyperlink from an external website pointing to your site, the primary off-page SEO signal for authority and trust.Read definition →Domain AuthorityMoz's proprietary 1–100 score predicting how well a domain will rank in search results, based on its backlink profile.Read definition →Page AuthorityMoz's 1–100 score predicting how well a specific page (not the whole domain) will rank in search results.Read definition →NofollowA link attribute (rel="nofollow") that tells search engines not to pass ranking credit (link equity) to the linked page.Read definition →DofollowA standard hyperlink (with no nofollow attribute) that passes ranking credit and link equity from the linking page to the destination.Read definition →Link JuiceThe informal SEO term for the ranking authority and equity passed from one page to another through a dofollow hyperlink.Read definition →
Local SEO
4 termsGoogle Business ProfileGoogle's free business listing tool that controls how a business appears in Google Search and Maps results.Read definition →NAP ConsistencyThe requirement that a business's Name, Address, and Phone number are identical across all online directories and citations.Read definition →Local CitationsAny online mention of a business's Name, Address, and Phone number, which helps search engines verify a local business's existence and prominence.Read definition →Local PackThe section of Google search results showing a map and three local business listings for queries with local intent.Read definition →
Frequently Asked Questions
What is the most important SEO concept to understand first?
Search intent — understanding what users actually want when they type a query — is the foundation of effective SEO. Every other optimization decision should flow from correctly identifying and matching search intent.
How many SEO terms do I need to know to start optimizing a website?
For basic on-page SEO, mastering about 10 core terms is sufficient: title tag, meta description, H1 tag, keyword density, internal linking, canonical URL, alt text, structured data, page speed, and backlinks.
Are these definitions applicable to Google, Bing, and other search engines?
The vast majority of these concepts apply across all major search engines, as they share the same foundational architecture (crawl, index, rank). Some specifics — like exact Core Web Vitals thresholds or specific schema types — are Google-centric, as Google is the dominant engine for most markets.