An event is a link between an occurrence in the system (such as a user action or a change in focus) and a piece of code that responds to that occurrence. The responding code is an event handler, and is nearly always written by the application developer. Events let application developers customize the behavior of components without having to change the classes themselves. This is known as delegation. 

Events for the most common user actions (such as mouse actions) are built into all the standard components, but you can also define new events. To create events in a component, you need to understand the following:

• What are events?
• Implementing the standard events
• Defining your own events

Events are implemented as properties, so you should already be familiar with the material in Creating properties before you attempt to create or change a component's events.