# SEO Vocabulary 2026: 100+ Essential SEO Terms and Definitions

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A simple SEO glossary covering 100+ essential terms, including keywords, technical SEO, backlinks, local SEO, AI search, analytics, and ranking factors.

## 100+ SEO Terms You Need to Know: The Complete Glossary at Best AISO

Understand the most important SEO vocabulary with simple 2-line definitions covering search, content, technical SEO, local SEO, AI search, and analytics at [Best AISO](https://bestaiso.com/)!

## SEO Essentials

**SEO = Search Engine Optimisation**  
The process of improving a website so it ranks higher in search engine results.  
It helps search engines understand your content and helps users discover your website.

**SMO = Social Media Optimisation**  
The process of improving social media profiles and content to increase visibility and engagement. It supports brand awareness, traffic, and overall online presence.

**CTR = Click-Through Rate**  
CTR is the percentage of people who click a search result, ad, or link after seeing it. A higher CTR usually means the title, description, or message is attracting more attention.

**E-E-A-T = Experience, Expertise, Authoritativeness, Trustworthiness**  
E-E-A-T is a Google framework for evaluating the quality and credibility of content. It considers the creator’s experience, expertise, authority, and trustworthiness.

**NLP = Natural Language Processing**  
NLP is technology that helps computers understand and process human language. Search engines use NLP to understand queries, content, entities, context, and meaning.

**CMS = Content Management System**  
A CMS is software used to create, manage, edit, and publish website content.  
WordPress, Shopify, and Drupal are common examples of CMS platforms.

**LSI = Latent Semantic Indexing**  
LSI is a mathematical technique for identifying relationships between words and documents. In SEO, "LSI keywords" is commonly used to mean related terms, although Google does not use LSI keywords as an SEO ranking factor.

## AI Optimisation & Performance

**AEO = Answer Engine Optimisation**  
AEO is the practice of creating content that directly answers questions in search and answer engines. It aims to make content easy for systems such as Google, Bing, and AI assistants to understand and cite.

**GEO = Generative Engine Optimisation**  
GEO is the practice of improving content visibility in AI-generated search results. It focuses on making information clear, trustworthy, structured, and easy for AI systems to reference.

**CRO = Conversion Rate Optimisation**  
CRO is the process of improving a website so more visitors complete desired actions. These actions can include purchases, sign-ups, downloads, or enquiries.

**PPC = Pay-Per-Click**  
PPC is an advertising model where advertisers pay when someone clicks their advertisement. Google Ads and Microsoft Advertising are common PPC platforms.

**ROI = Return on Investment**  
ROI measures how much profit or value an investment generates compared with its cost. In SEO, it can help measure whether organic search efforts generate business value.

**KPI = Key Performance Indicator**  
A KPI is a measurable metric used to track progress toward a specific business goal. SEO KPIs can include organic traffic, rankings, conversions, leads, and revenue.

**ROAS = Return on Ad Spend**  
ROAS measures the revenue generated for every unit of money spent on advertising. It is commonly used to evaluate the performance of paid search and other digital campaigns.

**CPA = Cost Per Acquisition**  
CPA measures how much it costs to acquire one customer or conversion. It is commonly used to evaluate paid marketing efficiency.

**CPC = Cost Per Click**  
CPC is the amount an advertiser pays for each click on an advertisement. It is a common metric in PPC campaigns.

**CPM = Cost Per Mille**  
CPM measures the cost of showing an advertisement 1,000 times. It is mainly used for measuring advertising reach and impressions.

## AI Tools & Tech Stack

**LLM = Large Language Model**  
An LLM is an AI model trained on large amounts of text to understand and generate language. LLMs power tools such as ChatGPT and can influence how people discover information online.

**GA = Google Analytics**  
Google Analytics is a platform used to measure website traffic, user behaviour, and conversions. It helps businesses understand how visitors find and interact with their websites.

**GSC = Google Search Console**  
Google Search Console is a free Google tool for monitoring a website's presence in Google Search. It provides data on search queries, clicks, indexing, crawling, and technical issues.

**API = Application Programming Interface**  
An API allows different software applications to communicate and exchange data. SEO tools often use APIs to access search, website, analytics, and performance data.

**XML = Extensible Markup Language**  
XML is a structured format used to store and exchange data. In SEO, XML is commonly used for XML sitemaps that help search engines discover URLs.

**HTML = HyperText Markup Language**  
HTML is the standard language used to structure content on web pages. Search engines use HTML elements to understand page content and structure.

**CSS = Cascading Style Sheets**  
CSS controls the visual appearance and layout of web pages. It affects elements such as colours, fonts, spacing, and responsive design.

**JavaScript = JS**  
JavaScript is a programming language used to create interactive and dynamic website features. Search engines may need to process JavaScript to access content and links on some websites.

**Schema Markup = Structured Data**  
Schema markup is code that helps search engines understand specific information on a webpage. It can describe products, articles, businesses, events, reviews, recipes, and other entities.

**JSON-LD = JavaScript Object Notation for Linked Data**  
JSON-LD is a format commonly used to add structured data to web pages. It helps search engines understand entities and relationships within website content.

## AI Visibility & Presence

**ASO = App Store Optimisation**  
ASO is the process of improving an app's visibility in app stores such as Google Play and Apple's App Store. It focuses on factors such as app titles, descriptions, keywords, ratings, and downloads.

**ORM = Online Reputation Management**  
ORM is the practice of monitoring and improving how a person or brand appears online. It includes managing reviews, mentions, search results, and public perceptions.

**SERP = Search Engine Results Page**  
A SERP is the page displayed by a search engine after someone enters a search query. It can contain organic results, ads, featured snippets, maps, images, videos, and other features.

**GEO = Geolocation SEO**  
Geolocation SEO improves visibility for searches connected to a specific geographic location. It helps businesses reach users searching for products or services in particular areas.

**AMP = Accelerated Mobile Pages**  
AMP was an open-source framework designed to create fast-loading mobile web pages. Google no longer gives AMP pages a special ranking advantage.

**URL = Uniform Resource Locator**  
A URL is the web address used to access a specific page or resource online. SEO-friendly URLs are usually clear, descriptive, and easy for users and search engines to understand.

**RSS = Really Simple Syndication**  
RSS is a format that allows users and applications to receive updates from websites automatically. It is commonly used for blogs, news sites, podcasts, and regularly updated content.

**Organic Search**  
Organic search refers to unpaid visibility in search engine results. Organic traffic comes from users who click non-paid search results.

**Search Visibility**  
Search visibility measures how prominently a website or brand appears across relevant search results. It can include rankings, impressions, SERP features, and visibility across multiple queries.

**Impressions**  
An impression occurs when a webpage, advertisement, or search result is displayed to a user. In Google Search Console, impressions show how often a page appeared in search results.

## Keywords & Search Intent

**Keyword**  
A keyword is a word or phrase that people use when searching for information online. SEO uses keywords to understand what users are looking for and create relevant content.

**Keyword Research**  
Keyword research is the process of finding and analysing search terms used by your target audience. It helps identify topics, search demand, competition, and content opportunities.

**Search Intent**  
Search intent is the reason behind a user's search query. Common types include informational, navigational, commercial, and transactional intent.

**Short-Tail Keyword**  
A short-tail keyword is a broad search term that usually contains one or two words. It often has high search volume but can also have strong competition and unclear intent.

**Long-Tail Keyword**  
A long-tail keyword is a more specific search phrase, usually containing several words. It typically has lower search volume but can have clearer intent and higher relevance.

**Primary Keyword**  
A primary keyword is the main search term a webpage is designed to target. It should closely match the page's topic and the user's search intent.

**Secondary Keyword**  
A secondary keyword is a related search term that supports the main topic of a webpage. It helps cover related questions, subtopics, and variations naturally.

**Keyword Difficulty**  
Keyword difficulty estimates how difficult it may be to rank for a particular search term. SEO tools calculate it using factors such as competition, authority, and backlink profiles.

**Search Volume**  
Search volume estimates how often people search for a particular keyword during a given period. It helps marketers evaluate the potential demand for a search topic.

**Keyword Cannibalisation**  
Keyword cannibalisation occurs when multiple pages on the same website compete for similar search queries. It can make it harder for search engines to determine which page should rank.

## On-Page SEO

**On-Page SEO**  
On-page SEO improves elements within a webpage to make its content more useful and understandable. It includes content, headings, titles, URLs, internal links, images, and HTML elements.

**Title Tag**  
A title tag is an HTML element that defines the title of a webpage. Search engines often use it as the main clickable title shown in search results.

**Meta Description**  
A meta description is an HTML element that summarises a webpage's content.  
Google may use it as the search result description, although it can choose other page text.

**H1 Tag**  
The H1 is the main heading of a webpage. It helps users and search engines understand the primary topic of the page.

**Heading Tags**  
Heading tags such as H1, H2, and H3 organise webpage content into a clear hierarchy. They improve readability and help search engines understand page structure.

**Alt Text**  
Alt text is descriptive text added to an image's HTML. It helps accessibility tools and search engines understand what an image represents.

**Internal Linking**  
Internal linking means linking from one page on a website to another page on the same website. It helps users navigate the site and helps search engines discover and understand related pages.

**External Link**  
An external link points from one website to a different website. Relevant external links can provide useful context and help users access supporting information.

**Anchor Text**  
Anchor text is the visible, clickable text used for a hyperlink. Descriptive anchor text helps users and search engines understand the linked page.

**Content Optimisation**  
Content optimisation improves content so it better satisfies user needs and search intent. It can involve improving accuracy, structure, relevance, readability, entities, and topical coverage.

## Technical SEO

**Technical SEO**  
Technical SEO improves the technical aspects of a website so search engines can crawl, understand, and index it. It includes site architecture, speed, mobile usability, JavaScript, indexing, and structured data.

**Crawling**  
Crawling is the process search engine bots use to discover and access webpages. Search engines crawl links, sitemaps, and other signals to find new or updated content.

**Indexing**  
Indexing is the process of storing and organising webpages in a search engine's database. A page generally needs to be indexed before it can appear in organic search results.

**Crawl Budget**  
Crawl budget refers to the amount of crawling resources a search engine allocates to a website. It is particularly relevant for large websites with many URLs.

**Robots.txt**  
Robots.txt is a file that gives search engine crawlers instructions about which URLs they may access. It does not reliably prevent a page from appearing in search results.

**Canonical URL**  
A canonical URL tells search engines which version of similar or duplicate pages is preferred. It helps consolidate signals when multiple URLs contain substantially similar content.

**Canonical Tag**  
A canonical tag is an HTML element that specifies the preferred URL for a page. It is commonly used to manage duplicate or near-duplicate URLs.

**Noindex**  
Noindex is a directive that tells search engines not to include a page in their search index. It is commonly used for pages that should remain accessible but should not appear in search results.

**Redirect**  
A redirect automatically sends users and search engines from one URL to another. Common SEO redirects include 301 permanent redirects and 302 temporary redirects.

**301 Redirect**  
A 301 redirect permanently redirects one URL to another URL. It is commonly used when a page has moved or URLs have been permanently changed.

**404 Error**  
A 404 error means a requested webpage could not be found on the server.  
Too many unnecessary broken links can create a poor user experience.

**HTTPS = HyperText Transfer Protocol Secure**  
HTTPS encrypts communication between a user's browser and a website.  
It improves security and is a standard expectation for modern websites.

**Core Web Vitals**  
Core Web Vitals are Google metrics used to evaluate aspects of webpage loading, responsiveness, and visual stability. The current metrics include LCP, INP, and CLS.

**LCP = Largest Contentful Paint**  
LCP measures how quickly the largest main content element becomes visible on a webpage. It is one of Google's Core Web Vitals for loading performance.

**INP = Interaction to Next Paint**  
INP measures how quickly a webpage responds to user interactions. It is one of Google's Core Web Vitals for responsiveness.

**CLS = Cumulative Layout Shift**  
CLS measures unexpected movement of content while a webpage loads. A lower CLS generally means the page provides a more stable visual experience.

**Mobile-First Indexing**  
Mobile-first indexing means Google primarily uses the mobile version of a website's content for indexing and ranking. Websites should provide equally important content and structured data across mobile and desktop versions.

## Off-Page SEO & Authority

**Off-Page SEO**  
Off-page SEO involves activities outside your website that can influence search visibility and reputation. It commonly includes backlinks, digital PR, brand mentions, and other external signals.

**Backlink**  
A backlink is a link from another website to your website. Quality, relevant backlinks can help search engines evaluate a site's authority and credibility.

**Link Building**  
Link building is the process of earning relevant backlinks from other websites.  
Common approaches include digital PR, useful resources, partnerships, and content promotion.

**Domain Authority**  
Domain Authority is a third-party SEO metric that estimates the ranking strength of a website's domain. It is a Google ranking factor.

**Page Authority**  
Page Authority is a third-party metric estimating the ranking strength of an individual webpage. It is not an official Google ranking factor.

**Referring Domain**  
A referring domain is a unique website that links to your website. A backlink profile can contain links from many referring domains.

**Link Equity**  
Link equity refers to the ranking value that may be passed through links between webpages. It is commonly discussed in relation to internal links and backlinks.

## Local SEO

**Local SEO**  
Local SEO improves a business's visibility for searches connected to a specific geographic area. It is especially important for businesses that serve customers at physical locations or specific service areas.

**Google Business Profile**  
Google Business Profile is Google's platform for managing how a business appears on Google Search and Maps. Businesses can provide information such as location, hours, services, photos, and reviews.

**NAP = Name, Address, Phone Number**  
NAP refers to the core business information used across websites and online directories. Consistent NAP information can help search engines understand and verify a local business.

**Local Pack**  
The Local Pack is a Google Search feature that displays local business listings for relevant searches. It commonly appears alongside a map and business information.

**Local Citation**  
A local citation is an online mention of a business's name, address, phone number, or other details. Citations can appear on directories, websites, local platforms, and business listings.

**Geo-Targeting**  
Geo-targeting delivers content, advertising, or search experiences based on a user's geographic location. It is commonly used in local SEO and paid advertising.

## AI Search & Generative Search

**AISO (AKA - AI SEO)**  
AISO is the practice of optimising content and websites for search experiences that use artificial intelligence. It can include traditional search, AI-generated answers, conversational search, and multimodal search.

**Generative Search**  
Generative search uses AI to generate answers or summaries instead of displaying only traditional search listings. Examples include Google's AI search experiences and other AI-powered search platforms.

**AI Overview**  
An AI Overview is an AI-generated summary that can appear within Google Search results. It combines information from multiple sources to provide a direct answer to a search query.

**AI Search Visibility**  
AI search visibility measures how often and where a brand or website appears in AI-generated search experiences. It can include mentions, citations, recommendations, and links within AI answers.

**AI Citation**  
An AI citation is a source reference or link used by an AI system to support information in an answer. Brands can improve citation opportunities by publishing clear, authoritative, and well-supported information.

**Entity**  
An entity is a distinct person, place, organisation, product, concept, or other identifiable thing. Search engines use entities to understand meaning and relationships beyond individual keywords.

**Knowledge Graph**  
A knowledge graph is a structured system that represents entities and relationships between them. Search engines use knowledge graphs to better understand people, organisations, places, topics, and facts.

**Semantic Search**  
Semantic search focuses on understanding the meaning and intent behind a query rather than matching keywords alone. It helps search engines return results that are contextually relevant to what the user wants.

**Query Expansion**  
Query expansion adds related terms or concepts to a search query to improve retrieval. Search engines can use related concepts, synonyms, entities, and context to understand what a user means.

**RAG = Retrieval-Augmented Generation**  
RAG is an AI approach that retrieves relevant information before generating an answer. It helps AI systems produce responses based on external or up-to-date sources.

## SEO Tracking

**Organic Traffic**  
Organic traffic is website traffic that comes from unpaid search engine results.  
It is one of the most common metrics used to measure SEO performance.

**Organic Conversion**  
An organic conversion occurs when a visitor from unpaid search completes a desired action. Examples include purchases, enquiries, registrations, downloads, and subscriptions.

**Bounce Rate**  
Bounce rate measures the percentage of sessions that meet the analytics platform's definition of an unengaged or single-page visit. Its exact calculation depends on the analytics system being used.

**Engagement Rate**  
Engagement rate measures the percentage of visits or users that meaningfully interact with a website. The exact definition varies by analytics platform.

**Average Position**  
Average position is a search performance metric showing the average position of a site's highest-ranking result for impressions. Google Search Console reports it as an aggregate metric rather than a simple ranking for every query.

**Search Query**  
A search query is the exact phrase or question a user enters into a search engine. Search queries provide insight into what people are looking for and how they discover content.

**Conversion Rate**  
Conversion rate is the percentage of users or visitors who complete a desired action. It is calculated by dividing conversions by the relevant number of users, sessions, or visits.

## Content & Site Structure

**Content Marketing**  
Content marketing uses useful and relevant content to attract, educate, and retain an audience. SEO helps this content become discoverable through search engines.

**Evergreen Content**  
Evergreen content remains useful and relevant for a long period of time.  
Examples include guides, tutorials, definitions, and foundational resources.

**Topical Authority**  
Topical authority refers to how comprehensively and credibly a website covers a particular subject. Building related, high-quality content can help demonstrate expertise around a topic.

**Topic Cluster**  
A topic cluster is a group of related pages organised around a central topic. A main pillar page connects to supporting pages that cover specific subtopics.

**Pillar Page**  
A pillar page provides a comprehensive overview of a broad topic. It usually links to more detailed pages covering related subtopics.

**Content Gap**  
A content gap is a topic or question that existing content does not adequately cover. Finding content gaps can reveal opportunities to create more useful pages.

**Duplicate Content**  
Duplicate content refers to substantially similar content appearing across multiple URLs. It can make it harder for search engines to determine which version to show in results.

**Thin Content**  
Thin content provides little unique value or fails to adequately satisfy the user's search intent. Improving depth, usefulness, accuracy, and relevance can make such pages stronger.

**Content Decay**  
Content decay occurs when a webpage gradually loses traffic, rankings, or relevance over time. Updating outdated information and improving the content can help recover performance.

## Search Features

**Featured Snippet**  
A featured snippet is a highlighted search result that directly answers a query near the top of Google's results. It can appear as a paragraph, list, table, or other format.

**Rich Result**  
A rich result is an enhanced Google Search result that displays additional information beyond a standard blue link. Structured data can make eligible pages available for certain rich result features.

**People Also Ask**  
People Also Ask is a Google Search feature containing related questions that users can expand to see answers. It can help SEO professionals discover related questions and content opportunities.

**Sitelinks**  
Sitelinks are additional links that Google may display beneath a main search result. They help users navigate directly to important sections of a website.

**Image Search SEO**  
Image SEO improves images so they can be discovered and understood by search engines. It includes descriptive filenames, alt text, relevant surrounding content, and suitable image formats.

**Video SEO**  
Video SEO improves videos and their surrounding webpages for visibility in search engines and video platforms. It can involve titles, descriptions, transcripts, structured data, thumbnails, and relevant content.

**AIO (AI Overviews)**  
AIO is an AI-generated search result that directly answers a query near the top of Google's results or ChatGPT. It can appear as a paragraph, list, table, or other format.

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