What is SEO and how it works PDF?

As you all know SEO stands for Search Engine Optimization, which is the practice of increasing the quantity and quality of traffic to your website through organic search engine results. It is the process of optimizing your online content so that a search engine likes to show it as a top result for searches of a certain keyword.
SEO is the magic you have to work on your article in order to make Google very likely to include your post as one of the top results whenever someone searches for that keyword. You might think of a search engine as a website you visit to type (or speak) a question into a box and Google, Yahoo!, Bing, or whatever search engine you’re using magically replies with a long list of links to webpages that could potentially answer your question.
That’s true. But have you ever stopped to consider what’s behind those magical lists of links? Now let’s understand how it works? Google or any search engine has a crawler that goes out and gathers information about all the content they can find on the Internet. The crawlers bring all those 1s and 0s back to the search engine to build an index. That index is then fed through an algorithm that tries to match all that data with your query.
There are a lot of factors that go into a search engine’s algorithm which decide the ranking. That’s all the Search Engine of SEO.
Now the O part of SEO is optimization – It is where the people who write all that content and put it on their sites are gussying that content and those sites up so search engines will be able to understand what they’re seeing, and the users who arrive via search will like what they see.
Optimization can take many forms. It’s everything from making sure the title tags and meta descriptions are both informative and the right length to pointing internal links at pages you’re proud of. 
I hope my answer is satisfying and you understand the SEO properly. For a more technical look at SEO, check out our website.