Amphetamines are a class of potent central nervous system (CNS) stimulants that include drugs such as amphetamine, methamphetamine, and dextroamphetamine. They are known for their ability to increase alertness, concentration, and energy. These substances are commonly used both medically, for conditions like Attention Deficit Hyperactivity Disorder (ADHD) and narcolepsy, and illicitly for their potent stimulating effects.