Google search results pages display sponsored links at the top and right, which are direct advertisements. These links are ads with keywords matching search keywords. Specific studies are conducted to optimize a site with search engines and to rank it on the first pages of search results. Just as a webmaster can do these studies themselves by providing backlinks, they can also advertise in the top or right sections of the Google search page for a fee. Yahoo also offers this service, similar to Google. This paid advertising service is called SEM, which stands for Search Engine Marketing, and it differs from SEO in this respect. It would be most appropriate to use SEM when the site is first established, for the purpose of introducing the site or to attract traffic for keywords with high competition. Providing intermittent ads instead of continuous advertising will ensure efficient use of SEM. When using SEM, applying the necessary SEO practices and obtaining useful backlinks will cause the site to climb in search results as the domain ages, and after a while, SEM will no longer be needed for a site that appears on the first page. Therefore, the most appropriate time to use SEM is when introducing the site.
