How do Google, Bing and Yahoo decide what websites are in their organic search results?

Broadly speaking, search engines aim to provide people with the most relevant information they are looking for. The search engine makes an educated guess based on the search term the user typed into the search box, the user’s location, personal preferences and more. The more specific the search string, the more relevant the search results become.

In order to fulfill its purpose to the searcher, the search engine has an application, called a spider or crawler, that walks from page to page through the Web and stores information about every page it finds. It stores all of this information in what is called the search engine’s index, which is a huge database of information. When you perform a search on Google, it will search its index and retrieve the most relevant web pages according to its algorithms. Yahoo and Bing will do the same. You often get different listings in different orders in the search results of each engine because each search engine is following its own proprietary algorithms.