There are a number of terms that you'll encounter in the realm of online advertising that are often used interchangably, or in a confusing manner. What's the difference between a pageview and a hit? Are ads that pay on a CPM basis more or less effective than those that pay on a per-click basis? For the answers to these and more, refer to our handy-dandy glossary of definitions below:

• Click
• CPM
• Hit
• Impression
• Pageview