Adwords Ranking

How does "Ranking" work in Google Adwords?

[MattyG]

My ads are not able to be shown because it says that my keyword ranking is too low... What does this mean and how can it be bettered?

Please help

[tomasvdb]

ad rank is the product of quality score and maxcpc. Increasing any of these factors will increase your adrank.

[MattyG]

Ok thank you very much...