Banner design tips : Call to action is one of the easiest ways to increase the CTR (click through rate) of a banner. Using a call to action simply involves having the words 'click here' or some other words such as 'sign up now' or something similar. All online ads have a link. The purpose is to get people to click on the ad and visit the advertiser's website. However with the world being so used to off-line advertising, many people just see banners and think that's it. They don't realize that they are actually meant to click on it to find out more. That's why having click here or another call to action improves the effectiveness of a banner.