Search Engine Optimization (SEO) is the process of refining a website so that it gets as many useful visits from search engines as possible. It can involve adding or restructuring content, changing the way it’s displayed, focusing on different keywords, or improving the code that runs behind the scenes.
The goals of SEO can be to rank highly when specific keywords are searched, to rank highly across a great number of long-tail keywords, to rank higher for keywords that are more specific to a niche, or to change the appearance of the site on search engines to make it more appealing.
While in the strictest definition SEO refers to on-site changes, most people think of it as an umbrella that includes link building and social media presence.