I have been in this blogging industry from almost three years and I have made money literally from many ways. But the most easiest is the display advertising, i.e. PPC and CPM ads, you install the ad code and hope to get clicks and impressions. But the most important thing is which ad size performs good for blogs. It is the 300 x 250 rectangle which takes the cake. It is the best revenue generator till date for all my blogs. The second comes the 728 x 90 leader board. These two ad formats have been performing great for all my blogs. The best part of these ad sizes is that they get mixed with the content and thus increases the chance of getting clicks. You can see these ads live in this post too. If you place these ads in the top rather than the bottom then again you are increasing your chances of getting clicks.
![[del.icio.us]](http://images.del.icio.us/static/img/delicious.small.gif){kind=small}
Can you tell me what are the difference between PPC and CPM ads?
Thanks in advance.
PPC ads are the ones which pays per click and CPM ads pay by the number of impressions. You can read more about them over here.