With this function you can check a position for a collision with another instance or all instances of an object. When you use this you are checking a single point in the room for an instance or an object. This check will be done against the bounding box of the instance or against the mask of the instance if that instance has precise collisions checked and will return the unique instance id. If you do not need the id of the colliding instance you should consider using position_meeting instead. This function also accepts the special keywords all and other and will return the keyword noone if no collision occurs.