Events are signals that something has happened to a part. These signals are sent to other parts.

An event might be a push button being clicked, the closing of a window, the starting of an application, the changing of an attribute value, or any number of other things done to a part.

As to connections, you use events to trigger actions or running of scripts. For example, you might connect the clicked event of a push button to the openWidget action of a new window. Then, when a user clicks on the push button, another window opens.