An autoattack (also called standard, normal, or basic attack) is the attack performed by a hero when right-clicking an enemy unit. Autoattacks are also performed by an idle hero when an enemy unit ventures too close to it, or when the "attack move" function is used (default right-click). Autoattacks are also performed by creeps.
When using attack-move, the hero stops to attack any hostile that gets in their way en-route to a destination. If a hero has an attack target, he or she will continue to attack it if in range and will move closer to it when out of range, until either a new target is specified, a cancel order is issued (pressing the H key or by specifying another move order), or they lose vision of the target.