How Search Engines Work
The first basic truth you should know to learn SEO is that search engines are not humans. While this is likely to be apparent for everyone, the variations between how people and search engines view internet pages aren’t. Unlike people, search engines are text-driven. Although technology advances rapidly, search engines are far from intelligent creatures that can feel the beauty of a cool design or enjoy the sounds and motion in movies. As an alternative, search engines crawl the Net, taking a look at particular website items (primarily text) to get an idea what a web site is about.
This brief rationalization is just not essentially the most exact because as we will see next, search engines carry out several actions as a way to deliver search outcomes – crawling, indexing, processing, calculating relevancy, and retrieving.
First, search engines crawl the Internet to see what’s there. This task is carried out by a bit of software, referred to as a crawler or a spider (or Googlebot, as is the case with Google). Spiders observe hyperlinks from one page to another and index the whole lot they find on their way. Having in thoughts the number of pages on the Net (over 20 billion), it is unattainable for a spider to go to a web site each day just to see if a brand new page has appeared or if an present web page has been modified, sometimes crawlers could not end up visiting your site for a month or two.
What you are able to do is to check what a crawler sees out of your site. As already mentioned, crawlers aren’t people and they don’t see photographs, Flash films, JavaScript, frames, password-protected pages and directories, so if you have tons of those on your web site, you’d better run the Spider Simulator under to see if these goodies are viewable by the spider. If they don’t seem to be viewable, they will not be spidered, not indexed, not processed, etc. – in a phrase they will be non-existent for search engines.
After a page is crawled, the subsequent step is to index its content. The listed page is saved in a large database, from where it may well later be retrieved. Primarily, the method of indexing is figuring out the phrases and expressions that greatest describe the page and assigning the page to particular keywords. For a human it is not going to be potential to course of such quantities of data but generally search engine deal simply effective with this task. Typically they might not get the which means of a web page right however if you happen to assist them by optimizing it, it will likely be easier for them to categorise your pages correctly and for you – to get higher rankings.
When a search request comes, the search engine processes it – i.e. it compares the search string in the search request with the listed pages in the database. Since it is doubtless that a couple of page (virtually it’s tens of millions of pages) comprises the search string, the search engine starts calculating the relevancy of each of the pages in its index with the search string.
There are numerous algorithms to calculate relevancy. Every of these algorithms has totally different relative weights for frequent factors like key phrase density, links, or metatags. That is why totally different search engines give totally different search results pages for the same search string. What’s more, it’s a recognized fact that every one main search engines, like Yahoo!, Google, Bing, AOL, etc. periodically change their algorithms and if you wish to keep on the top, you additionally need to adapt your pages to the latest changes. That is one cause (the other is your rivals) to commit permanent efforts to search engine marketing, if you would like to be at the top.
The final step in search engines’ activity is retrieving the results. Principally, it is nothing more than simply displaying them within the browser – i.e. the limitless pages of search outcomes that are sorted from the most related to the least relevant sites.
2. Differences Between the Major Search Engines
Although the basic precept of operation of all search engines is similar, the minor variations between them result in main changes in outcomes relevancy. For different search engines different factors are important. There have been times, when SEO consultants joked that the algorithms of Bing are deliberately made simply the opposite of these of Google. While this might have a grain of reality, it is a matter a undeniable fact that the most important search engines like totally different stuff and if you plan to overcome multiple of them, you need to optimize carefully.
There are lots of examples of the variations between search engines. For example, for Yahoo! and Bing, on-page keyword components are of major significance, while for Google links are very, very important. Additionally, for Google sites are like wine – the older, the higher, while Yahoo! generally has no expressed choice in the direction of websites and domains with tradition (i.e. older ones). Thus you might need extra time till your web site gets mature to be admitted to the highest in Google, than in Yahoo!
