An event is caused by an action such as the click of the mouse. You use events to initiate code. To use an event, you simply open an object and hit create event. Below is a list of common events used by all game creators using "Game Maker."
List of Important Events
Create Event: The create event is ran right when that object is created. used to set local variables (Next Chapter)
Destroy Event: This event is ran when your object is destroyed (instance_destroy()).
Alarm: An alarm event is run after a timer hits 0 (alarm[0] = 60; //steps)
Step Event: A step event runs ever step, every second, all the time. All code in here runs over and over.
Collision: A collision event is activated on collision with another object.
Keyboard: A keyboard event runs as long as the key is down, as soon as you release that code stops.
Key Pressed: Runs the code once the key is hit. Unlike the keyboard event, it only runs once until you press again.
Key Released: Runs the code on release of a key.
Mouse: There are several actions that all involve the mouse. if normal mouse is used, you need to click the object. If you use the global mouse, you can click anywhere.
Joystick: You can find this under mouse. You can set up your game with game controllers and joy sticks. Pretty sweet.
Other: contains multiple events that you can check out. I will explain a few of the important ones for you.
Room/Game Start/end: This code is run at the start/end of the room/game. It is useful for running codes you only want ran once.
Animation end: Runs once the animation of a sprite ends.
Draw: The draw event is used to draw to your screen. You can show text, sprites, and other things with it.