In a previous article, we simply defined what a CPM was. It is simply the cost per 1000 impressions of an advertisement. This is the most common type of display advertising campaigns. They tend to allow for the greatest reach and prevent people from getting into the "last click dilemma". Display advertising is about influencing a customer and not always getting them to click. So a CPM allows you to get in front of, and influence your customers anywhere on the web they might be.
Now with that said, it is important to do a thing like frequency cap how many ads a customer will see in a specific time. In some instances, I have personally seen 30 ads for one company in moments. That was a horrible brand experience! We recommend a frequency cap of 3 to 4 ads per 4 or 8 or 12 hours. With placing these caps it helps broaden your reach by showing fewer ads to more people. Now if you want to get in front of your customers a lot, take the caps off and let the impressions fly!