How search engines works

How search engines work?

The first basic truth you wish to grasp to find out SEO is that search engines aren't humans. whereas this may be obvious for everyone, the variations between however humans and search engines read websites are not. not like humans, search engines area unit text-driven. though technology advances quickly, search engines area unit removed from intelligent creatures that may feel the sweetness of a cool style or relish the sounds and movement in movies. Instead, search engines crawl the online, gazing explicit web site} things (mainly text) to induce a thought what a site is regarding. This temporary clarification isn't the foremost precise as a result of as we'll see next, search engines perform many activities so as to deliver search results – creeping, indexing, processing, hard relevance, and retrieving.

First, search engines crawl the online to visualize what's there. This task is performed by a bit of package, known as a crawler or a spider (or Googlebot, as is that the case with Google). Spiders follow links from one page to a different and index everything they realize on their manner. Having in mind the amount of pages on the online (over twenty billion), it's not possible for a spider to go to a website daily simply to visualize if a brand new page has appeared or if Associate in Nursing existing page has been changed, generally crawlers might not find yourself visiting your website for a month or 2.

What you'll do is to envision what a crawler sees from your website. As already mentioned, crawlers aren't humans and that they don't see pictures, Flash movies, JavaScript, frames, password-protected pages and directories, therefore if you've got plenty of these on your website, you'd higher run the Spider machine below to visualize if these goodies area unit seeable by the spider. If they're not seeable, they'll not be spidered, not indexed, not processed, etc. - during a word they'll be non-existent for search engines.

After a page is crawled, subsequent step is to index its content. The indexed page is keep during a big info, from wherever it will later be retrieved. basically, the method of compartmentalisation is distinguishing the words and expressions that best describe the page and distribution the page to explicit keywords. For somebody's it'll not be potential to method such amounts of data however usually search engines deal simply fine with this task. generally they may not get the which means of a page right however if you facilitate them by optimizing it, it'll be easier for them to classify your pages properly and for you – to induce higher rankings.

When a probe request comes, the program processes it – i.e. it compares the search string within the search request with the indexed pages within the info. Since it's doubtless that over one page (practically it's voluminous pages) contains the search string, the program starts hard the relevance of every of the pages in its index with the search string.

There area unit varied algorithms to calculate relevance. every of those algorithms has completely different relative weights for common factors like keyword density, links, or meta tags. that's why different search engines provide different search results pages for constant search string. what's additional, it's a celebrated incontrovertible fact that all major search engines, like Yahoo!, Google, Bing, etc. sporadically modification their algorithms and if you would like to stay at the highest, you furthermore might have to be compelled to adapt your pages to the newest changes. this can be one reason (the different is your competitors) to devote permanent efforts to SEO, if you would like to be at the highest.

The last step in search engines' activity is retrieving the results. Basically, it's nothing over merely displaying them within the browser – i.e. the endless pages of search results that area unit sorted from the foremost relevant to the smallest amount relevant sites.