What value is used to determine whether your ad will show on a page and, if so, the ad’s position?
Quality Score
Quality Factor
Ad Rank
Ad Score
Explanation:
A value that’s used to determine your ad position (where ads are shown on a page relative to other ads) and whether your ads will show at all. Your Ad Rank is recalculated each time your ad is eligible to appear and competes in an auction, so your ad position can fluctuate each time depending on your competition, the context of the person’s search, and your quality at that moment.
Read more here: https://support.google.com/adwords/answer/1752122
