SEO is a free marketing technique that can helps marketers, bloggers, webmasters, researchers to ranking their website contents, web pages for a some particular and specific keywords.
For this purpose, you’ve a strong ability to do keyword research. Because without a proper keyword research you never ever getting higher ranking in search engine.
SEO has two main categories :
On-Page SEO
Off-Page SEO
and these are done via two popular techniques which are known as :
White-hat SEO
Black-hat SEO
SEO contains are dozens of factors which helps you to getting higher ranking in search engine like Google, Bing, Yahoo etc.