This SEO Glossary by Kasra Dash defines every essential term, acronym, and concept you’ll encounter in Search Engine Optimisation.

Use it as your quick-reference guide as you explore the Learn SEO series — from beginner fundamentals to advanced technical concepts.

Bookmark this page — it’s your SEO dictionary, training manual, and internal link map all in one

How to Use This Glossary

Each term is written in plain English, linked contextually to deeper guides within the Learn SEO library, and grouped by theme.

• Core SEO Concepts → How search engines and ranking work.
• On-Page SEO → How to optimise what’s on your site.
• Off-Page SEO → How external signals influence trust.
• Technical SEO → How your site communicates with crawlers.
• AI & Modern SEO → How machine learning and semantic systems impact visibility.
• Metrics & Tools → How to measure performance.

Core SEO Concepts

Algorithm → A set of rules and AI systems (like RankBrain and BERT) that determine which web pages appear for specific searches. Learn more in What Are Search Engine Algorithms.

Crawling → The process where Googlebot or other search engines discover and scan web pages via links or sitemaps. Covered in How SEO Works.

Indexing → When a search engine stores information about a page in its database so it can appear in search results. Explained in What Is Google Indexing.

Ranking Factors → The signals algorithms use to decide which pages rank higher — such as relevance, backlinks, and usability. See SEO Ranking Factors.

SERP (Search Engine Results Page) → The list of results that appears after a user performs a search. Includes organic results, featured snippets, and paid ads.

Search Intent → The underlying goal behind a search query — informational, navigational, or transactional. Central to What Are Keywords.

SEO (Search Engine Optimisation) → The practice of improving website visibility in organic search. Start with What Is SEO.

SEM (Search Engine Marketing) → A broader term encompassing both SEO (organic) and PPC (paid). Compared in SEO vs SEM vs PPC.

PPC (Pay Per Click) → Paid advertising model where you pay per click, used within SEM.

E-E-A-T → Google’s framework for evaluating Experience, Expertise, Authoritativeness, and Trustworthiness. Core to Why SEO Matters.

On-Page SEO Terms

Alt Text → Descriptive text added to images for accessibility and SEO context.

Anchor Text → The clickable words in a hyperlink that describe the linked page’s content.

Canonical Tag → A tag that tells Google which version of a duplicate page is the “master.”

Content Optimisation → The process of improving readability, relevance, and keyword alignment. Detailed in Content SEO.

Header Tags (H1–H6) → HTML tags that structure content hierarchically.

Meta Description → A short summary of a page (under 160 characters) shown in SERPs.

Meta Title / Title Tag → The clickable headline in search results.

Schema Markup → Code that helps search engines understand your content and display rich results.

Slug → The final part of a URL (e.g., /learn/what-is-seo/).

Internal Linking → Links connecting pages within your own website, distributing link equity and improving crawlability.

Keyword Density → The percentage of times a keyword appears within content — less relevant today; focus on semantic intent.

LSI Keywords → Related terms that reinforce topical context.

Readability → How easy your text is to read; affects engagement and time on page.

User Experience (UX) → Design and usability signals that influence engagement and indirectly impact SEO.

Off-Page SEO Terms

Backlink → A link from another website to yours, acting as a trust signal.

Domain Authority (DA) → A metric developed by Moz to estimate ranking potential.

PageRank → Google’s original algorithm measuring link value and distribution.

Anchor Relevance → The topical similarity between the linking and linked content.

Digital PR → Acquiring backlinks through press coverage, stories, or data campaigns.

Citation → A business mention (with NAP — Name, Address, Phone) used in Local SEO.

Link Equity → The value or authority passed through internal or external links.

NoFollow / DoFollow Links → Attributes determining whether a link passes SEO authority.

Toxic Links → Low-quality backlinks from spammy sites that can harm rankings.

Link Velocity → The speed at which a site gains or loses backlinks — unnatural patterns can trigger algorithmic filters.

Reputation Management → SEO strategies that influence how your brand appears online.

Technical SEO Terms

Canonicalisation → Preventing duplicate content by specifying preferred URLs.

Crawl Budget → The number of pages Googlebot will crawl on your site within a timeframe.

Core Web Vitals → Google’s metrics for user experience: Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS).

HTTPS → Secure protocol indicating encrypted communication; a confirmed ranking factor.

Robots.txt → A file telling crawlers which pages to access or ignore.

XML Sitemap → A file that lists your site’s pages for better discovery and indexing.

Site Architecture → The way your pages are organised and linked.

Server Response Codes → HTTP codes like 200 (OK), 301 (redirect), 404 (not found).

Structured Data → JSON-LD or Microdata that defines entities and relationships for search engines.

Index Coverage → The ratio of indexed to total submitted pages; measured in Search Console.

Mobile-First Indexing → Google’s approach to prioritising mobile versions of content.

PageSpeed / Load Time → How quickly a page renders; part of Core Web Vitals.

→ Deepen your understanding in Technical SEO and How SEO Works.

Technical SEO ensures your website can be found, understood, and trusted by search engines.

AI & Modern SEO Terms

AI Overviews (SGE) → Google’s AI-generated answers that summarise information directly in search results.

RankBrain → Machine learning system that helps Google interpret search queries.

BERT (Bidirectional Encoder Representations from Transformers) → NLP model improving Google’s understanding of language and intent.

MUM (Multitask Unified Model) → AI system that understands text, images, and context across languages.

Helpful Content System → Algorithm that prioritises people-first content over SEO spam.

Entity SEO → Optimising around people, places, and concepts rather than just keywords.

Knowledge Graph → Google’s database connecting entities and facts for rich search results.

Semantic SEO → Structuring content around meaning and relationships instead of single terms.

E-E-A-T (Revisited) → A core component of algorithmic trust, especially in YMYL topics.

→ For in-depth coverage, visit AI & SEO and What Are Search Engine Algorithms.

AI doesn’t replace SEO — it evolves it.

SEO Tools & Metrics

Ahrefs → Popular SEO platform for backlinks, keyword research, and competitor analysis.

Semrush → Comprehensive tool for SEO, PPC, and content research.

Screaming Frog → Website crawler for auditing technical SEO issues.

Google Analytics → Measures traffic, engagement, and conversion metrics.

Google Search Console (GSC) → Monitors indexing, performance, and technical errors directly from Google.

CTR (Click-Through Rate) → Percentage of users who click a result after seeing it.

Bounce Rate → Percentage of users who leave a page without interaction.

Impressions → How often your site appears in search results.

Conversion Rate (CVR) → Percentage of visitors completing a desired action.

Average Position → The mean ranking for your keywords over a given period.

CPC (Cost Per Click) → Average cost of each click in a PPC campaign.

ROI (Return on Investment) → Measurement of profit relative to SEO spend.

Keyword Difficulty (KD) → Metric estimating how hard it is to rank for a keyword.

→ See How Long Does SEO Take and SEO Strategy for Beginners for practical context.

Marketing & Strategic Terms

Brand Authority → The degree of trust and recognition your brand commands online.

CRO (Conversion Rate Optimisation) → Improving the percentage of visitors who take meaningful actions.

Content Marketing → Creating useful content to attract and retain audiences organically.

Digital PR → A subset of link building that uses storytelling and media coverage.

Topical Authority → How comprehensively your site covers a subject area — a growing ranking signal.

User Intent → The “why” behind a search query; dictates keyword strategy.

Zero-Click Searches → Queries answered directly on the SERP (via snippets or AI summaries).

Summary: The Language of Search

This glossary isn’t just definitions — it’s your SEO translation key.
Every term connects to a system, strategy, or signal within the search ecosystem.

By mastering this vocabulary, you can read algorithm updates, evaluate tools, and communicate SEO strategy with confidence.

→ Next: put this knowledge into practice with SEO Strategy for Beginners.

The more you understand SEO language, the more fluent you become in visibility itself.