What is a Banner Ad?
A Banner Ad is the sometimes present graphical rectangle at the top of a website that advertises something and provides a link to the advertiser's site.
What's the Danger?
Although most banner ads are legitimate advertisements without any malicious intent, there is no way to know beforehand what exactly will happen when you click on them. Banner Ads may entice you to download unwanted files or link to pop-ups. The safest policy is to use already trusted sites or search engines to find what you are looking for.
Are They Effective?
There is some debate about how effective they really are. An article by MarketingTerms.Com states that the amount of banner ad clicks has been steadily declining for various reasons, but that they can still be a useful and profitable investment if done tactfully.