Alter was a group of Force powers in the teachings of the Jedi Order. Regarded as an advanced form of using the Force, it was taught to Jedi Knights after they had learned the fundamentals of Control as Jedi Initiates and Sense as Padawans. The Alter discipline involved manipulating objects, influencing other beings, and affecting the environment. Many non-trained Force-sensitives stumbled upon such abilities accidentally, which usually resulted in disastrous events. The Jedi described not progressing to the Alter discipline as being able to perceive the Force but not manipulate it.
The fundamental Alter techniques were telekinesis, affect mind, and Alter Environment. Telekinesis was the core ability which included Force push and Force pull. Affect mind could override the impulses of the weak-minded, and Alter Environment allowed the user to control the natural environment. This could include summoning a whirlwind, lightning, or other natural phenomena.