This is one of those internet buzzwords that everyone talks about and in our 20+ years of experience in the web and software development field, has found that the only true way to guarantee your website will be on the first page of Google or other search engine is to pay lots of money to have it as an advert.
Most search engines run "Organically" (sorry... another internet buzzword) which is to say that certain criteria is met in order to find your website.
This includes keywords in the web address as well as in the content of the page.
If you Google search for "search engine optimization" at the time we created this page the first result (not a paid advert) is a wikipedia.org page about the subject and not one of the search engine optimization companies that "guarantee" that they can get you to the first page... (funny that)