What is the difference between white hat, grey hat and black hat SEO/Link Building?

Do you know What is a reciprocal link? Are they still effective as a link building strategy?

What are the benefits of using content marketing to build links? What are some examples?

What are NoFollow links and DoFollow links in seo?

Does any one knows What is PageRank, and is it important?

What is the difference between link building and link buying?

How long does it take for link building to improve my site's rankings?

Does any one can tell me Why Is Link Building Important for the site?