Basically, a search engine algorithm is a set of rules, or a unique formula, that the search engine uses to determine the significance of a web page, and each search engine has its own set of rules. These rules determine whether a web page is real or just spam, whether it has any significant data that people would be interested in, and many other features to rank and list results for every search query that is begun, to make an organized and informational search engine results page. The algorithms, as they are different for each search engine, are also closely guarded secrets, but there are certain things that all search engine algorithms have in common.
1. Relevancy – One of the first things a search engine algorithm checks for is the relevancy of the page. Whether it is just scanning for keywords, or looking at how these keywords are used, the algorithm will determine whether this web page has any relevancy at all for the particular keyword. Where the keywords are located is also an important factor to the relevancy of a website. Web pages that have the keywords in the title, as well as within the headline or the first few lines of the text will rank better for that keyword than websites that do not have these features. The frequency of the keywords also is important to relevancy. If the keywords appear frequently, but are not the result of keyword stuffing, the website will rank better.
2. Individual Factors – A second part of search engine algorithms are the individual factors that make that particular search engine different from every other search engine out there. Each search engine has unique algorithms, and the individual factors of these algorithms are why a search query turns up different results on Google than MSN or Yahoo!. One of the most common individual factors is the number of pages a search engine indexes. They may just have more pages indexed, or index them more frequently, but this can give different results for each search engine. Some search engines also penalize for spamming, while others do not.
3. Off-Page Factors – Another part of algorithms that is still individual to each search engine are off-page factors. Off-page factors are such things as click-through measurement and linking. The frequency of click-through rates and linking can be an indicator of how relevant a web page is to actual users and visitors, and this can cause an algorithm to rank the web page higher. Off-page factors are harder for web masters to craft, but can have an enormous effect on page rank depending on the search engine algorithm.