When you set up your business / service, you tend to search for target prospective customers. There might be many people, as prospective clients, who you do not know of. It is in such cases that you would need search engine optimization or SEO, to help you reach out to and establish a connection with clients. Search engine optimisation is, simply put, the mode of drawing traffic to your web page.
For example, you are selling raincoats and you have not optimised your site. Chances are, due to high competition, a buyer is likely to contact those companies appearing on the first few pages of Google search over yours. With search engine optimisation, we optimise phrases and words like raincoat manufacturers and improve the chances of your website appearing higher up in search engine rankings.
A well written and relevant introduction, headline and content can increase user dwell time and thus rankings.
Is important. If you optimise the wrong keywords, you will be drawing traffic through those wrong keywords.
Do a check on the search volume of your keywords
Google takes your mobile version of your website to be your primary website so ensure your website is responsive.