Ads that appear on the first page or above tend to get significantly more clicks than ads that appear on deeper search result pages. To get your ads into these valuable positions, Microsoft Advertising offers cost-per-click (CPC) bid estimates for you to use while setting up your bids.
In the Keywords tab, you will find 3 kinds of bid estimates available to help get your ad on the first page when a search query matches your keywords exactly.
First page bid estimate: The bid you likely need to set for your ad to show anywhere on the first page search results.
Mainline bid estimate: The bid estimate you likely need to set for your ad to show among the ads on the mainline of search results.
Best position bid estimate The bid you likely need to set for your ad to be shown in the first position at the top of the first page of search results.
First page, mainline, and best position bid estimates show the bid you will likely need for your ad to reach your preferred placement in search results for the device or devices you are targeting. For example, if your campaign only runs on mobile devices, the first page bid estimate will reflect the bid likely required to reach the first page of the search results on mobile devices.
Even if you met the bid estimate for your placement, there might be times that your ads do not appear in the search result placements that you preferred. These estimates are guidelines based on your keyword’s Quality Score and recent advertiser competition so meeting or exceeding these bid estimates isn’t a guarantee of where your ad will appear. Here are a few common reasons your ad may not show on the first page, even if you meet the bid estimate:
Advertiser competition: There could be new competition on your keywords.
Keyword match: Your keywords might not match up exactly with what customers are searching.
Budget changes: Your ad may not be read if your recently changed budget is fully depleted.