A reflex reaction is something that your body does in response to a stimuli, such as a hit or a scare. You personally have no conscious control over the reaction. Like when someone hits your knee and your leg bounces, or when you touch a hot stove and you instantly draw your hand away. its a reaction that your brain doesnt have to think about, your body just does it automatically. Its called a reflex because it is not something you think about doing like picking up an apple, its something your body does all on its own whether you think about it or not!