When creating your keywords, Microsoft Advertising provides you suggested bids for some of the most desirable ad positions. Given that it is almost always preferable to have your ad on the first page of Microsoft Bing com or Yahoo.com search results, Microsoft Advertising checks specifically for bids that will not result in a first page placement. Microsoft Advertising will provide a warning in the Keywords table (in the Delivery column) if, based on the last seven days of data from the search network, your bid is not adequate to put your ads on the first page of the search results page.
The bid amount is deducted from your campaign budget each time your ad is clicked. The actual cost for each keyword or placement varies depending on the following: