How do I know if my online banner and search ads are really effective?

There are several metrics that need to be understood in order to determine the effectiveness of banner ads. First, is the audience clicking on the ad and getting to your website (click thrus,) or are they viewing your ad and searching for your website (view thrus.) Is one particular creative implementation better than another? When someone lands on your website, what do they do? Stay, look around or leave? How long do they stay and what do they look at? The answer to these questions and others can be understood through tracking the user from the point where an ad is displayed through all the actions they take as they interact with that ad and then your website. Tracking and analysis is the key to determining and increasing your return on investment (ROI) and is what drives efficiencies in the online world.