Event-driven programming concentrates on the events (messages) and their flow between different software components. If you think about it longer, you'll notice that the notion of events can be found in many types of software. Historically, event-based programming is the most common paradigm for software that deals with direct human interaction. It means that it is a natural paradigm for graphical user interfaces. Everywhere the program needs to wait for some human input, that input can be modeled as events or messages. In such framing, an event-driven program is just a collection of event or message handlers that react to human interaction.
Events also don't have to be a direct result of user interaction. The architecture of any web application is also event-driven. Web browsers send requests to web servers on behalf of the...
