SEO is short for search engine optimization or if you are referring to the person doing the work search engine optimisation.
Search engine optimization is a popular methodology that combines different strategies, tactics and techniques with the purpose of increasing the amount of visitors to a website. This is being achieved by obtaining a high placement in the ranking of the search results page of a search engine, otherwise known after the short version of SERP. The most popular search engines to date are Google, Bing or Yahoo.
The ranking of a site in a search is essential for directing more visitors toward the site due to the fact that it is well known Internet users don’t click through pages and pages of search results. The chance for a user to visit a site increases proportionally with the higher it ranks in the organic results of a search.
SEO make a website more accessible to a search engine and it greatly raises the chances for a website to be found by search engines. SEO usually combines different sets of “white hat” techniques and best practices that will help the site achieve a better ranking in the SERP (search engine result pages).