Actors are GalaxyEdit's data editor's way of linking graphics and sounds together to form what you can see and hear on the map. They include units, attacks, models, text, sounds, range indicators, terrain deformations, and more. They are possibly the most important thing in the data editor, but also one of the most complicated things.
Actors don't do anything unless you have events. Events are like triggers; you need a condition, and if the condition is met, an action happens. For example, on unit birth, you want the unit model to be created. When the unit is ordered to move, you want it to stop playing its idle animation or firing animation before it starts walking. When the unit attacks, you want to have it use a specific attack animation depending on what it attacks, and perhaps a particular sound played. All this is controlled with actor events.
MORE TO COME, WIP.