Ad group
From The Yaffe Center
An ad group contains one or more ads as well as keywords. When searcher enters a query that is similar to or contains a keyword within the ad group, the ad group is determined to be relevant. If the quality score (partially determined by relevance) is high enough the search engine will show an ad within the ad group. One bid can be placed for each keyword in an ad group, or different bids can be placed for individual keywords within the ad group.