SEO is typically divided into two main groups –

On page SEO: Everything on the page. This includes all the content that you put up on your website and the HTML tags that tell the Search Engines about your content. This aspect of SEO is completely under your control.

Off page SEO: Everything off the page. This primarily includes all the links that come to your website from other websites. This is partially in your control however with great strategy it can help achieve your SEO objective.