WebmasterQuery

Search engines will index your site sooner or later without needing SEO, and you can see this through your website's logs, which reveals unknown search engines visiting because they know about your site either through the records in your domain registry or following certain patterns from free hosts/subdomains services if you have you have not a fully qualified domain name.

However, SEO is important to get your site indexed on top of other results and therefore a potential visitor can see it at first glance.

SEO is important as it aims to research the needs and behaviors of the searchers in order to present the most relevant content on the top spots of the search engine results on the right time in the right place and in the right situation. The main goal of  an SEO specialist is to provide SEO for clients in a way that they earn more money by placing their content, products and services in positions where the searchers are expecting such things to be when they need it the most.