Search Advertising

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. 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.

Search advertising is sold and delivered on the basis of keywords. The user of a search engine enters keywords to make queries. A keyword may consist of more than one word. Search engines conduct running auctions to sell ads according to bids received for keywords and relative relevance of user keywords to ads in the inventory. The keyword “home mortgage refinancing" is more expensive than one that is in less demand, such as “used bicycle tires.” Profit potential of the keywords also plays into bids for ads that advertisers want displayed when the keywords are searched by the user. For example, "used book" may be a popular keyword but may have low profit potential and the advertiser bids will reflect that.

Search engines build indexes of Web pages using a web Crawler. When the publisher of a Web page arranges with a search engine firm to have ads served up on that page, the search engine applies their indexing technology to associate the content of that page with keywords. Those keywords are then fed into the same auctioning system that is used by advertisers to buy ads on both search engine results pages. Advertising based on keywords in the surrounding content or context is referred to as Contextual advertising. This is usually less profitable than search advertising which is based on user intent expressed through their keywords.