CPC and CPM are two ways to pay for ads, and they work differently. With CPC, you pay only when someone clicks on your ad. This is useful if your main goal is to get traffic to your offer. CPM means you pay for every one thousand times your ad is shown, even if nobody clicks. CPM is often used when you're trying to build brand awareness or reach a large audience. If your ad has a high click-through rate, CPC can give better results. But if your banners are more about being seen, then CPM might work well. It depends on what you are trying to achieve with your campaign. What has worked better for you between the two?