Search engine marketing is a process by which websites gain greater traffic through both paid and unpaid promotions on search engines. Search engine marketing primarily focuses on paid promotional efforts, with unpaid promotions making up a small fraction of the effort expended on marketing campaigns.
Paid promotions are offered by most major search engines, and typically involve ads for a website being placed near or at the top of search results for a particular keyword or phrase. Paid promotions may be charged by the click or by the ad impression depending on what type of ad is purchased. Unpaid promotions, on the other hand, focus primarily on tailoring a website's content so that it is easy for search engines to index. This process is referred to as search engine optimization.