In Internet Marketing, Search Advertising is a method of placing online advertisements on Web pages that show results from search engine queries. Through the same search-engine advertising services, ads can also be placed on Web pages with other published material.

Search advertisements are targeted to match key search terms (called keywords) entered on search engines. This targeting ability has contributed to the attractiveness of search advertising for advertisers. Consumers will often use a search engine to identify and compare purchasing options immediately before making a purchasing decision. The opportunity to present consumers with advertisements tailored to their immediate buying interests encourages consumers to click on search ads instead of unpaid search results, which are often less relevant. Unpaid search results are also called organic results

An online advertising network or ad network is a company that connects advertisers to web sites that want to host advertisements. The key function of an ad network is aggregation of ad space supply from publishers and matching it with advertiser demand.