The Internet has brought speed to business and a revolution in the relationship among citizens. With millions of pages, the Web represents an environment for commercial relationships among several sections of the Economy. Interactivity is a differential feature of this new medium. Propaganda is, therefore, inevitable. Companies try to annouce their products and services through different kinds of advertisements. These advertisements aim at informing and persuading the internet users to accomplish their goals. Among the types of advertisement in the Web, we can find the pop-up banner, overlapping the contents of interfaces of Web sites, especially during downloading. In many cases, we notice that the users close the banners ignoring their messages. In this situation, it is relevant to understand how the communication between the user and the banner happens, considering the principles of the semiotic process of the language of the design, which interfere in the fulfillment of the correct usability.