glossary

Plain-language definitions for SEO and AI-search terminology.

A

Anchor text: The clickable text of a hyperlink. Used by search engines as a relevance signal for the linked page; over-optimised exact-match anchors can trigger penalties.
AI Overview: A generative AI answer shown at the top of Google's search results, synthesised from multiple sources with citations. Often produces zero-click outcomes for informational queries.
Algorithm update: A change to how a search engine ranks results. Google deploys broad core updates several times per year; smaller updates are continuous.
Alt text: The text alternative for an image, used by screen readers and search engines. Should describe the image accurately and concisely.
AS (Authority Score): Semrush's proprietary score (0-100) estimating a domain's overall SEO authority, combining link, traffic, and quality signals.

B

Backlink: A hyperlink from another website pointing to yours. One of the strongest ranking signals; quality matters more than quantity.
Black hat SEO: Tactics that violate search engine guidelines: cloaking, sneaky redirects, automated content generation, link schemes. Carries penalty risk.
Bounce rate: The percentage of visits where the user leaves without further interaction. A weak SEO signal in isolation; context dependent.
Breadcrumbs: A navigation aid showing the user's location within a site hierarchy. Often marked up with BreadcrumbList schema for SERP display.

C

Canonical tag: An HTML element (`<link rel="canonical">`) declaring the preferred URL when multiple URLs serve substantially the same content.
Citation (local): An online mention of a business including its name, address, and phone number (NAP). Important for local pack ranking.
CLS (Cumulative Layout Shift): A Core Web Vitals metric measuring unexpected layout shifts during page load. Good: under 0.1.
Cluster (content cluster): A group of pages covering related sub-topics, linked back to a central pillar page. Builds topical authority.
Core Web Vitals: Google's set of three user experience metrics used as ranking signals: LCP (load speed), INP (interactivity), and CLS (visual stability). Introduced as a ranking factor in 2021.
Crawl budget: The number of URLs a search engine crawler will fetch on a site within a given period. A constraint primarily for very large sites.
Crawlability: The degree to which search engine bots can access and fetch the pages of a site.
CTR (Click-Through Rate): The percentage of impressions that result in a click. A primary measure of SERP performance.

D

DA (Domain Authority): Moz's proprietary score (0-100) estimating a domain's link-based authority. Not used by Google directly.
Disavow file: A file uploaded via Search Console listing backlinks Google should ignore. Useful for manual action recovery; widely overused otherwise.
Dofollow: A link without rel="nofollow". Passes link equity normally. The default state of any link.
DR (Domain Rating): Ahrefs' proprietary score (0-100) for a domain's link profile strength. Logarithmic; not used by Google directly.
Duplicate content: Substantially identical or very similar content appearing at multiple URLs. Dilutes ranking signals across pages; resolved with canonical tags, redirects, or consolidation.

E

E-E-A-T: Experience, Expertise, Authoritativeness, Trustworthiness. Google's quality framework, particularly stringent for YMYL content.
Entity SEO: Optimising for search engines and AI systems that reason about real-world entities (people, organisations, products) rather than keywords.

F

Featured snippet: A search result format where Google extracts and displays a passage from a ranking page directly in the SERP, above the standard organic results.
FID (First Input Delay): A former Core Web Vital measuring responsiveness to the first user interaction. Replaced by INP in March 2024.

G

GBP (Google Business Profile): Google's free local business listing, the primary asset for local pack and Google Maps visibility. Formerly Google My Business.
GEO (Generative Engine Optimisation): The practice of structuring content for retrieval and citation by AI answer engines. Overlaps with traditional SEO; emphasises entity clarity and direct-answer formats.
Googlebot: Google's web crawler. Operates in two-pass indexing: initial HTML processing, then JavaScript rendering.
Google-Extended: Google's user agent for AI training data collection, separate from Googlebot. Can be blocked in robots.txt without affecting search indexing.
GSC (Google Search Console): Google's free webmaster tool providing data on indexing status, search performance, crawl errors, and manual actions. The primary diagnostic interface between site owners and Google.

H

Heading tags: HTML elements (H1 through H6) marking the structural hierarchy of page content. The H1 signals the primary topic; lower levels organise sub-sections. A modest on-page ranking signal.
Hreflang: An HTML attribute (or sitemap element) declaring the language and regional targeting of a page. Manages multilingual and multi-regional sites.
HSTS (HTTP Strict Transport Security): An HTTP header that forces browsers to use HTTPS for the domain. Strong commitment; cannot be quickly reversed.

I

Indexing: The process by which a search engine stores and organises crawled pages, making them eligible to appear in search results.
INP (Interaction to Next Paint): A Core Web Vitals metric measuring overall page responsiveness to user interactions. Good: under 200ms.
Internal link: A hyperlink from one page on a site to another page on the same site. Distributes PageRank and signals topical structure.

J

JavaScript SEO: The discipline of ensuring search engines can crawl, render, and index content delivered via JavaScript.

K

KD (Keyword Difficulty): A score (0-100) estimating how hard it is to rank for a query, typically based on the link profiles of currently ranking pages.
Keyword stuffing: Repetitive, unnatural use of target keywords in content. Damages readability; flagged by quality systems.
Knowledge graph: A database of entities and their relationships used by Google (and AI systems) to answer entity-based queries.
Knowledge panel: An information box about an entity (person, organisation, place) shown alongside search results, drawn from Google's knowledge graph.

L

LCP (Largest Contentful Paint): A Core Web Vitals metric measuring perceived load speed via the largest visible element. Good: under 2.5 seconds.
Link equity (PageRank): The authority a page passes through its outbound links. The basis of Google's original ranking algorithm; still influential.
Link velocity: The rate at which a site acquires new backlinks over time. Sudden spikes can appear unnatural and attract algorithmic or manual scrutiny.
llms.txt: A proposed Markdown file at the root of a domain providing an AI-readable index of a site's most important content. Not yet a formal standard.
Log file analysis: The process of parsing server access logs to understand exactly which URLs search engine bots crawled, at what frequency, and which were skipped. More reliable than crawl simulation tools.
LocalBusiness schema: Schema.org structured data declaring a business's local entity properties: name, address, phone, hours, services.
Local pack: The map and three business listings shown at the top of search results for queries with local intent.
Long-tail keyword: A specific, often longer search query with low individual volume but typically clearer intent and lower competition.

M

Manual action: A penalty issued by Google's spam team after human review. Reported in Search Console; requires reconsideration request to lift.
Meta description: An HTML attribute summarising a page for search engines and link previews. Not a direct ranking factor; influences CTR.
Mobile-first indexing: Google's policy of using the mobile version of a site as the primary version for indexing and ranking. Standard since 2019.
Mojibake: Text corrupted by character encoding mismatches, typically appearing as garbled symbols (e.g. â€" instead of an em dash).

N

NAP: Name, Address, Phone. The core business information that must be consistent across local citations for local SEO.
Noindex: A meta tag (or HTTP header) instructing search engines not to index a page. Pages must be crawlable for the directive to be seen.
Nofollow: A link attribute (`rel="nofollow"`) telling search engines not to pass link equity through the link. Used for sponsored, user-generated, or untrusted links.

O

Off-page SEO: Optimisation activities that happen outside a site: link building, digital PR, brand mentions, citations.
On-page SEO: Optimisation of elements on individual pages: title tags, headings, content, internal linking, schema.
Open Graph: Meta tags (og:title, og:description, og:image) controlling how a URL appears when shared on social media and messaging platforms.
Organic search: Search results not paid for by advertising. Organic traffic is the audience SEO is built around.
Orphan page: A page with no internal links pointing to it. Difficult for crawlers to discover and receives no internal link equity.
Outbound link: A hyperlink from a page on your site to a page on a different domain. Passes link equity if dofollow, and signals topical associations to search engines.

P

PageRank: Google's original algorithm for valuing pages based on the quantity and quality of inbound links. Still influential, though heavily evolved.
Pagination: Splitting long content or lists across multiple pages. Affects crawl, indexing, and how authority flows through a site.
Passage indexing: Google's ability to index and rank individual passages within a page independently of the page's overall topic, allowing relevant sections to surface for specific queries.
PBN (Private Blog Network): A network of sites created specifically to manipulate link equity. Violates Google's guidelines.
Pillar page: A comprehensive overview page on a topic, linking to deeper cluster pages on specific sub-topics.

Q

Query: The words or phrase a user types into a search engine. Distinct from 'keyword' in that a query is what the user typed; a keyword is what the SEO targets.

R

Redirect (301): An HTTP status code indicating a permanent URL change. Transfers ranking signals to the destination URL.
Redirect (302): An HTTP status code indicating a temporary URL change. Does not transfer ranking signals.
Redirect chain: A sequence of redirects (URL A → URL B → URL C). Reduces signal transfer and adds latency. Best avoided.
Rendering: The process of executing JavaScript and producing the final DOM. Googlebot renders pages in a separate pass after initial HTML processing.
Rich result: An enhanced search result with visual elements (star ratings, FAQ accordions, recipe cards, product information) driven by structured data.
Robots.txt: A plain text file at the root of a domain declaring which crawlers can access which paths. A request, not enforcement.

S

Schema markup: Structured data using the schema.org vocabulary, declaring the meaning of page content explicitly to search engines and AI systems.
Search intent: The underlying goal behind a query: informational, navigational, commercial investigation, or transactional.
Search volume: The estimated number of times a keyword is searched per month within a given market. A primary input in keyword research alongside keyword difficulty.
SEO (Search Engine Optimisation): The practice of improving a site's visibility in unpaid search results.
SERP (Search Engine Results Page): The page returned in response to a search query, including organic results, ads, and SERP features.
Sitemap: An XML file listing the URLs of a site, providing search engines with a catalogue for crawling.
Sitelinks: Additional links to sub-pages shown beneath a brand's main search result. Algorithmically generated; not directly controllable but influenced by site structure and internal linking.
Soft 404: A page returning a 200 OK status code but containing content that signals it should be a 404. Confuses indexing.
Structured data: Machine-readable metadata embedded in a webpage. Most commonly delivered as JSON-LD using schema.org vocabulary.

T

Thin content: Pages with little or no unique value: doorway pages, scraped content, auto-generated text, or pages with minimal original material. A quality signal targeted since the Panda era.
Title tag: The HTML element (`<title>`) defining a page's title. Appears in browser tabs, SERPs, and link previews. One of the most influential on-page ranking factors.
Topic cluster: A group of related pages organised around a pillar page, used to build topical authority.
Topical authority: A measure of how comprehensively and credibly a site covers a subject area, built through depth of content and internal linking structure. Influences rankings across a topic regardless of individual page signals.

U

UGC (rel=ugc): A link attribute (`rel="ugc"`) indicating the link was created by a user, such as in comments or forum posts. Introduced alongside rel=sponsored in 2019 as a refinement of nofollow.
URL (Uniform Resource Locator): The address of a webpage. Clean, descriptive URLs reinforce topical relevance and improve usability.

V

Viewport meta tag: An HTML meta tag (`<meta name="viewport">`) controlling how a page scales on mobile devices. Essential for passing mobile-friendliness signals.
Voice search: Searches performed by speaking to a device rather than typing. Tends towards conversational, longer-tail, and question-format queries.

W

WebP: An image format with better compression than JPEG and PNG. Recommended for most web image use cases.
White hat SEO: SEO tactics that comply with search engine guidelines. Sustainable; carries no penalty risk.

X

XML sitemap: An XML-formatted sitemap providing search engines with a list of canonical URLs to crawl. See also: Sitemap.

Y

YMYL (Your Money or Your Life): Content categories Google scrutinises with stricter E-E-A-T standards: medical, financial, legal, safety, civic.

Z

Zero-click search: A search where the user finds the answer in the SERP itself (via featured snippet, knowledge panel, or AI Overview) without clicking through.