Microsoft adCenter (formerly known as MSN adCenter) provides pay-per-click (PPC) advertisements in search results on BING. Similar to Google AdWords, Microsoft adCenter uses both the maximum amount an advertiser is willing to pay-per-click on their ad, and the advertisement’s click-through rate (CTR) to determine how frequently an advertisement is shown. This system encourages advertisers to writer effective ad-copy and to advertise only on searches which are relevant to their particular...