Summary: out by other ads This insures fairness for each advertiser There will also never be more than 10 ads displayed at any given time Visitors will always see your ad on each impression You will need to supply your own graphic gif or jpg are both fine It needs to be exactly 125x125 pixels If you need one created for your program you can get one created at scriptlance
Image Dimensions: 288 x 325
Image originally found here.