CPM stands for Cost per thousand (Mille) impressions.
RPM stands for Revenue per thousand (Mille) impressions.
In other words, CPM is the price you'd pay each time your ad has been seen 1,000 times.
Fun facts:
‘Mille’ means thousand in Latin
The 'M' in CPM is the Roman numeral for 1,000
For additional terminology and key performance indicators for measuring success, please see:
For examples on calculating your ECPM (Earnings per thousand impressions), see: