Chapter Glossary

Chapter Glossary

Search Engine

A system that discovers, processes, and retrieves web content in response to a user query. It operates through three sequential phases: crawling, indexing, and ranking.

Crawler (Googlebot)

An automated program that follows links across the web to discover and retrieve page content for processing. Google's primary crawler is called Googlebot.

Crawl Budget

The number of pages a search engine will crawl on a given site within a set period. Sites with many low-quality or duplicate pages may find important content crawled infrequently as a result.

Index

The search engine's database of processed and stored web pages. A page must be in the index to be eligible to appear in search results.

Indexing

The process by which a search engine analyses a crawled page and stores it in the index, including its content, structure, and relationships to other pages.

Ranking

The process of ordering indexed pages in response to a specific query, based on evaluated signals including relevance, authority, and technical accessibility.

PageRank

Google's original algorithm for evaluating the quality and authority of a page based on the number and quality of links pointing to it. It shifted search from keyword matching toward quality evaluation.

Ranking Signal

Any factor a search engine uses to evaluate a page's suitability for a given query. Signals are grouped broadly into on-page relevance, off-page authority, and technical accessibility.

Search Intent

The underlying goal or need behind a search query. Search engines attempt to identify intent in order to return results that match what the user actually wants, not just the words they typed.

E-E-A-T

Experience, Expertise, Authoritativeness, and Trustworthiness. A framework used in Google's quality evaluation guidelines to assess the credibility of a page and its creator.

Core Web Vitals

A set of page experience signals measuring loading speed, visual stability, and interactivity. Confirmed as ranking signals by Google as part of the Page Experience update.

Algorithm Update

A change to the rules or signals a search engine uses to rank content. Major updates typically target a specific quality problem, such as low-quality content (Panda) or manipulative links (Penguin).

Panda Update

A 2011 Google algorithm update targeting low-quality, thin, or duplicate content. It reduced rankings for sites with poor content quality across large portions of their pages.

Penguin Update

A 2012 Google algorithm update targeting manipulative link-building practices. It reduced rankings for sites with unnatural or low-quality backlink profiles.

Hummingbird Update

A 2013 overhaul of Google's core algorithm that improved the engine's ability to interpret the meaning of a query as a whole, rather than matching individual keywords.

BERT

A 2019 update applying a natural language processing model that improved Google's understanding of how words relate to each other within a query, particularly for conversational or complex searches.

Helpful Content Update

A Google update introducing site-wide quality signals that assess whether content is created primarily to help users or primarily to rank in search. Sites with high proportions of unhelpful content are affected across all pages.

Noindex Tag

An instruction placed in a page's code that tells search engines not to include that page in the index. A crawled page with a noindex tag will not appear in search results.

Robots.txt

A file on a website that instructs crawlers which pages or sections they are allowed to access. Blocking important pages here prevents them from being crawled and indexed.

Canonical Tag

An HTML element that tells search engines which version of a page is the preferred one when similar or duplicate versions exist. A page pointing its canonical to another URL may not be indexed independently.

Personalisation

The adjustment of search results based on individual user signals such as location, device type, and search history. It means two users searching the same query may see different results.

Mobile-First Indexing

Google's approach of using the mobile version of a page as the primary version for crawling and indexing, reflecting the dominance of mobile search behavior.

Topical Relevance

The degree to which a page or site is focused on a coherent subject area. Search engines use topical signals to assess whether a source has genuine depth and authority on a given topic.

Backlink

A link from one website to another. Backlinks from credible, relevant sources are a confirmed signal of authority used in ranking evaluation.

Spam Detection

The methods a search engine uses to identify and discount or penalise content or links that appear designed to manipulate rankings rather than serve users.