I’ve slightly introduce once on SEO. And, to know how SEO works, you have to ‘make friend’ with search engines and understand the way search engines work.

How do search engines work?

For search engines, they read text but not images, sounds and videos. Unlike humans, they don’t see authentic-designed images. So, you don’t expect they will study your site/ blog which mostly made up of no-alt-text images and get any idea of what your site is about. Though they are pretty good enough to crawl over billions of sites which is not a man-could-do task, search engines are still unable to read images yet.

In brief, search engines they undergo several processes or activities to convey you search results for particular keyword you typed in. These processes are crawling, indexing, classifying, counting keywords relevancy, arranging and delivering results.

Crawling

Nowadays, there are billions of site are already existing on the internet. No matter blogspot, .com, .net, .org and so on, they are too many for search engines to view them in a day time. If you’re lucky enough, then your site might be crawled frequently, however, if not, then you can’t do anything but wait quietly for search engines’ “arrival”.

Indexing

After crawling on your web, search engines are now indexing your website into a gigantic database. If you ask me how big it will be, I don’t have any answer though. However, imagine that it can keep billions of data which are progressively increasing everyday, thereby you should know how big it will be.

Classifying

Let’s say your data are now delivered into a database. Now, your data will undergo classification according to keywords relevancy. i.e. If you search for "dogs" in google, then dogs' results (dogs-related website) will appear but not radios and so on.

Counting keywords relevancy

Actually, classifying process of search engines is quite related to this. They start classifying your site according to keywords. If your topic have higher keyword relevancy than others’ sites for the particular search query, then you might get above the others in ranking of the search results.

Arranging and delivering results

As I mentioned, if you had a higher relevancy than others, then you will most likely get above of them. And, what you’ve searched today are the results that undergo several processes above. So, by now you should be able to understand basic function/working of search engines.