A "Mouse Event" refers to actions performed by a user with a computer mouse, such as clicking, moving, or scrolling. These events are essential for interacting with graphical user interfaces (GUIs) in software applications and websites. Common types of mouse events include click, dblclick, mousemove, and scroll, each triggering specific responses in the program. When a mouse event occurs, it generates an event object that contains information about the action, such as the position of the cursor and the button pressed. Developers use this information to create interactive features, enhancing user experience in applications and websites.