SEO website optimization is a set of techniques used to increase the visibility of a website on google search and allows you to ultimately increase sales of your product or service.
The first stage is called On-page optimization and involves the preparation of a complete website for the Google algorithm - the use of special techniques that will allow Google to understand your website and place it with end users in accordance with their search terms.
The second stage is Off-page optimization and involves link building methods that raise the authority of your pages on Google search and thus give a signal to the algorithm that this page is very important for the user.