Banner ads are a form of online advertising that display visual advertisements on web pages. They work by linking to a website to generate traffic and can also inform, notify, and increase brand awareness. The effectiveness of banner ads is measured by their click-through rate, which is the percentage of impressions that result in clicks. Sharenet is a good place for brands to purchase banner ads because it has a large, mature, and affluent audience in South Africa that is receptive to advertising.