Google Quality Score

Google Quality Scores reflect Landing Page Content relevance to Keywords.

Quality Score Factors are:

Click Through Rate of the Keyword and Matched Ad
Click Through Rate of the Entire Account
Account Performance in the Geographically Area the Ad is Shown
Keyword Relevance with Respect The Entire Ad Group
Landing Page Quality and Relevance (Essentially, On-page "SEO" for that Keyword)
Ad Copy-Keyword Congruence
Secret Stuff Google Won't Tell Us

Google displays good Quality Score advertisements more frequently and/or in higher positions. More Click-Throughs to your web site and lower PPC per-unit costs result. Your ads rank is determined by your Bid and your Quality Score. Therefore, Higher Quality Score = Better Placement at the Same Cost

Quality Scores help Google display PPC ads linking to relevant, useful landing pages. Google wants customers to find their PPC ads relevant and useful. Advertisers and Google have shared interest in PPC ads that are relevant to search terms.

By using multiple Campaigns, Ad Groups, Ads, and Landing Pages, you can help create specifc Ads and Landing Pages that are very relevant for specific keywords

Read More and See Example Code