Why am I showing Adsense CPM Ads Instead of CPC?

Wondering why your website or blog is only showing CPM Adsense ads instead of CPC?  First, CPM stands for cost per thousand impressions (the M is the roman numeral 1000).  That means an advertiser is paying every time the ad is displayed on your site, whereas CPC only pays when clicked.  CPM ads compete with CPC ads for every Adsense Auction on your site, meaning you may or may not get CPM