Search Engine Indexing (OCR A-Level Computer Science): Revision Notes

Search Engine Indexing

Overview

Search engine indexing is the process of organising and storing information about web pages so that they can be quickly retrieved and ranked in response to a user's search query. Indexing is essential for search engines, as it allows them to scan and deliver relevant results efficiently. A key part of this process is determining the relevance and authority of web pages using algorithms like PageRank.

What is Search Engine Indexing?

• Purpose: Indexing allows search engines to store information about billions of web pages, making it possible to retrieve relevant results quickly when users perform a search.
• Process: Search engines use automated programmes called web crawlers (or spiders) to visit and analyse web pages. These crawlers "crawl" the web, moving from link to link to discover new content.
• Storage: Once a page is discovered, information about it (such as keywords, metadata, and content) is stored in the search engine's index, which is a massive database of web pages.

Why is Indexing Important?

• Indexing helps search engines organise web content in a way that allows them to quickly match relevant results to user queries.
• Without indexing, search engines would have to scan the entire internet every time a search is made, which would be inefficient and time-consuming.

The Crawling and Indexing Process

• Crawling: Web crawlers scan and analyse web pages, following links to discover new content. Crawlers revisit pages periodically to check for updates.
• Parsing: The content of each page, including text, keywords, headings, images, and metadata, is analysed and broken down into elements the search engine can interpret.
• Storing in Index: The parsed information is stored in the search engine's index. This index allows the search engine to retrieve relevant pages based on keywords in the user's query.