Plain-English SEO Glossary: 60 Terms Without the Jargon

SEO has an unusually large jargon surface for a field that mostly comes down to "make useful pages and let search engines find them." A lot of the vocabulary is genuinely useful shorthand. Some of it is vendor marketing dressed up to sound like a Google feature. This glossary defines 60 terms in one or two plain sentences each, grouped by theme, and flags the handful that are more marketing than mechanism.

It is meant to be skimmed and searched, not read start to finish. Where a term has a full guide behind it, there is a link.

Crawling and indexing

Crawling. The process where a search engine's bot fetches your pages by following links. If a page is never crawled, it cannot be indexed or ranked.

Indexing. Storing a crawled page in the search engine's database so it can appear in results. Crawled and indexed are separate steps; a page can be crawled and then not indexed.

Crawl budget. The rough number of pages a search engine will crawl on your site in a given period. Only a real concern for very large sites; small sites almost never hit the limit.

Googlebot. Google's web crawler. It fetches pages, renders them, and passes them to indexing. Its user-agent identifies it, and you can control what it accesses in robots.txt.

Robots.txt. A text file at your domain root that tells crawlers which paths not to crawl. It controls crawling, not indexing, a blocked page can still appear as a bare URL. See the robots.txt guide.

Noindex. A meta tag or HTTP header telling search engines to keep a page out of the index. Unlike robots.txt, it actually removes the page from results, but the page must be crawlable for the engine to see the tag.

XML sitemap. A file listing your URLs to help search engines discover them. It is a hint for discovery, not a command to index.

Canonical tag. A <link rel="canonical"> that tells search engines which URL is the primary version among duplicates or variants. See the canonical tags guide.

Orphan page. A page no internal links point to. Hard for crawlers to discover and a common reason pages sit unindexed.

Crawl error. A failure when a bot tries to fetch a URL, such as a server error, a broken redirect, or a timeout. Reported in Search Console.

Rendering. The step where Google runs a page's JavaScript to see the final content. If key content only appears after client-side rendering, Google may index a blanker version than users see.

Soft 404. A page that returns a 200 OK status but looks empty or "not found" to Google. Either add real content or return a proper 404 status.

On-page and content

Title tag. The <title> element, the clickable headline in search results and the biggest on-page relevance and click signal. Keep it under roughly 60 characters so it does not truncate. Our character counter checks the length.

Meta description. The <meta name="description"> snippet shown under the title in results. Not a ranking factor, but it affects click-through. Aim for roughly 150–160 characters.

H1. The main heading of a page, usually the visible title. One clear H1 per page is the sensible default. Our heading analyzer shows your heading structure.

Heading hierarchy. The nesting of H1 through H6 that gives a page an outline. Logical nesting helps both readers and crawlers understand structure.

Alt text. The alt attribute describing an image for screen readers and search engines. Describe the image plainly; skip "image of."

Anchor text. The clickable words of a link. It tells search engines what the linked page is about, so descriptive anchors beat "click here."

Internal link. A link from one page on your site to another. The main way crawlers discover pages and how you pass context and authority around your own site. See internal linking strategy.

Keyword. A word or phrase people type into search. In practice, the topic and intent behind the phrase matter more than the exact string.

Search intent. What the searcher actually wants, informational, commercial, navigational, or transactional. Matching intent is more decisive than matching keywords.

Keyword density. The percentage of a page's words that are your target keyword. An obsolete metric; there is no target number, and stuffing hurts.

Structured data. Machine-readable markup (usually JSON-LD) that describes a page's content to search engines. Can enable rich results. See the schema markup guide.

Schema.org. The shared vocabulary of types (Article, Product, FAQPage) used for structured data, maintained jointly by Google, Microsoft, Yandex, and others.

Rich result. An enhanced search listing (star ratings, FAQ dropdowns, recipe cards) generated from structured data. Google decides whether to show one; valid markup makes eligibility possible, not guaranteed.

Featured snippet. A boxed answer pulled from a page and shown above the normal results. Earned by clearly answering a question, not by markup.

Thin content. A page with little unique value, boilerplate, near-duplicate, or auto-generated. A common reason for "Crawled - currently not indexed."

Duplicate content. Substantially identical content on multiple URLs. Rarely a penalty, but it splits signals and forces search engines to pick a canonical for you.

Cannibalization. When two of your own pages compete for the same query, so neither ranks as well as one consolidated page would.

E-E-A-T. Google's shorthand for Experience, Expertise, Authoritativeness, and Trust, criteria its quality raters use to judge content. Not a direct score in the algorithm, but a useful lens.

Links and authority

Backlink. A link from another site to yours. Still one of the stronger ranking signals when the linking site is relevant and trusted.

Inbound link / external link. Inbound links come from other sites to you; external links go from your site out to others. "Backlink" specifically means an inbound one.

Link equity. The ranking value passed through a link, informally "link juice." Relevant, trusted links pass more.

Nofollow. A rel="nofollow" attribute telling search engines not to pass ranking credit through a link. Now treated as a hint rather than a strict rule.

Sponsored / UGC. Link rel values marking paid links (sponsored) and user-generated ones (ugc). Use them to label links honestly and avoid link-scheme trouble.

Anchor text (link context). See above under on-page, the words in a backlink also tell Google what your page is about, which is why unnatural anchor patterns look manipulative.

Link building. The practice of earning or acquiring backlinks. Earning them through genuinely useful content ages better than buying them.

Domain Authority (DA). A Moz-invented 0–100 score predicting ranking ability. It is a third-party metric, not a Google signal, Google does not use or recognize it. Useful only for rough comparison, and easy to over-index on.

Domain Rating (DR). Ahrefs' equivalent of DA. Same caveat: a vendor metric based on Ahrefs' link index, not something Google calculates.

PageRank. Google's original link-analysis algorithm, still conceptually part of ranking. The public PageRank toolbar score was retired in 2016; anyone quoting a "PageRank number" today is quoting nothing real.

Toxic links. A vendor framing for backlinks a tool judges harmful. Google largely ignores spammy links automatically, so most "toxic link" cleanup and disavowing is unnecessary for normal sites.

Link farm. A network of low-quality sites that exist to sell or trade links. Association with them is a genuine risk, unlike most "toxic link" scares.

Metrics and analytics

Impressions. How many times your page appeared in search results for any query. A Search Console metric.

Clicks. How many times searchers clicked through to your page from results.

Click-through rate (CTR). Clicks divided by impressions. A low CTR on a well-ranked page often means the title or description is not compelling.

Average position. The mean ranking position of your page across the queries it appeared for. Averaged, so a "position 8" can hide a mix of 3s and 20s.

Organic traffic. Visits from unpaid search results, as opposed to paid, direct, or referral traffic.

Bounce rate. In older analytics, the share of visits with no second interaction. GA4 replaced it with engagement rate; not a direct Google ranking factor either way.

Conversion rate. The share of visitors who complete a goal (purchase, signup). A business metric, not an SEO ranking input, but the reason SEO matters.

SERP. Search Engine Results Page, everything Google shows for a query, including ads, snippets, and the ten blue links.

Core Web Vitals. Google's page-experience metrics: LCP (loading), INP (responsiveness), and CLS (visual stability). A real but modest ranking input. See Core Web Vitals explained.

LCP, INP, CLS. Largest Contentful Paint (time to render the main content), Interaction to Next Paint (responsiveness to input), and Cumulative Layout Shift (how much the layout jumps). The three Core Web Vitals.

AI and generative search

AI Overview. Google's AI-generated answer shown at the top of some results, summarizing sources. It can reduce clicks to the underlying pages even when it cites them.

GEO. Generative Engine Optimization, shaping content so AI answer engines (ChatGPT, Perplexity, Google's AI Overviews) cite it. Overlaps heavily with ordinary good SEO; treat grand "GEO" claims skeptically.

Answer engine. A tool that returns a synthesized answer instead of a list of links, ChatGPT, Perplexity, Claude. The target of GEO.

LLMs.txt. A proposed file listing your most important content for large language models, analogous to a sitemap. Adoption is early and no major AI vendor commits to reading it yet. See the LLMs.txt guide. Our LLMs.txt generator builds one.

AI crawler. A bot that fetches pages to train or ground AI models, such as GPTBot or ClaudeBot. You can allow or block them in robots.txt, separately from search crawlers.

Grounding / citation. When an AI answer links back to the source it drew from. Being cited is the AI-search equivalent of ranking, and it still depends on being crawlable and clearly written.

Hallucination. When an AI confidently states something false. Relevant to SEO because AI Overviews occasionally misattribute or misquote the pages they summarize.

Frequently Asked Questions

Is Domain Authority a real Google ranking factor?

No. Domain Authority is a 0–100 score invented by Moz (and Domain Rating is Ahrefs' version) to predict ranking ability from their own link data. Google does not calculate, use, or recognize either one. They are useful only as rough third-party comparisons, and it is easy to chase them at the expense of things Google actually measures.

What's the difference between crawling and indexing?

Crawling is a bot fetching your page by following links. Indexing is storing that page in the search engine's database so it can appear in results. They are separate steps: a page can be crawled and then left out of the index on quality grounds, which is why "crawled - currently not indexed" is a common Search Console status.

Does keyword density still matter?

No. Keyword density, the percentage of words on a page that are your target term, is an obsolete metric with no target number. Modern search engines understand topics and intent, so writing naturally about a subject matters far more than hitting a keyword percentage, and stuffing keywords actively hurts.

What is E-E-A-T and is it a ranking factor?

E-E-A-T stands for Experience, Expertise, Authoritativeness, and Trust, the criteria Google's human quality raters use to judge content. It is not a direct score in the ranking algorithm, but it describes the kind of signals Google's systems try to approximate, so it is a useful lens for content quality, especially on health, finance, and safety topics.

Do I need an LLMs.txt file for AI search?

Not urgently. LLMs.txt is a proposed standard for listing your key content for large language models, but adoption is early and no major AI vendor commits to reading it yet. It costs little to add, so it is reasonable to include one, but being crawlable and clearly written does far more for AI citation today.