How Do Search Engines Work
So you open your browser, you go to Google and you type in your search and get a list of really relevant businesses just itching to have you as a client! It’s easy right – but how does it work? Is it magic? Is it random? Is it based on who pays Google the most money?
Well, it’s ‘none of the above’. It’s all based on a strict, tried and tested process which uses evolving criteria to determine which sites offer the most valuable and relevant information for those who are searching. Understanding how the search engines work is the first step to understanding how to approach your search engine optimisation.
Crawling
Search engines use programs called robots (also known as spiders or bots) which view individual web pages, retrieve the information from the page they are designed to retrieve and log it against the URL of the page for later analysis. They find the web pages they view by looking at the links on the web pages they are viewing and logging them for future viewing (this is often immediate). These programs are often referred to as ‘spiders’ because they ‘crawl’ along the links of the ‘web’.
Indexing
Once the search engines have the pages cached, they then create an index of the pages. This index is in the form of a ‘look up table’ of pages relevant to particular words. Words are given associations (often words that have relevance to each other) and pages which fit these associations can then be indexed against them.
Ranking
When a user searches within Google the system looks for every page within the index that directly fits the search or is associated with the search and then in real-time ranks the pages against each other using a range of over 200 factors, which they have logged for each page. These criteria include PageRank, level of association, number of times the search query appears on the page, authority of the page and occurrence in Meta data or title tags.
As you can see from the above the process is fairly well defined. Yes, it is true that the detail of the ranking process is unknown and could if you are sceptical be open to some unfair manipulation to favour people who spend money with Google (for example) but all the evidence suggests this is not the case. It is not magic although the algorithm (if we were ever allowed to see it) would probably seem like alchemy to the layman and it certainly isn’t random, otherwise the results would be very poor indeed.
