SEO is essentially the process of taking actions on your site by analysing exactly what is wrong or what could be improved on your site. The objective it to optimise all elements so that it is looked upon more favourably by search engine algorithms, and exactly how to go about implementing those changes. Usually your site would be reviewed by a Digital Marketing expert who can audit and evaluate everything on your site and give you a breakdown of the work that needs to be done if you ever hope to achieve those ever-coveted top spots on the likes of Google or Bing. Essentially, this is what will make your site easier to find by people searching relevant terms.
As every business is different, however, every website and its individual goals will be completely different and this has to be factored into any successful SEO strategy. Thankfully, digital marketers are not limited to a single way of working or technique and a wide variety of different ways of improving your websites search engine presence now exist. It is important to remember that the complexity, time and money involved in one site's SEO may be wildly different from another.