Caffeine
Caffeine is a central nervous system (CNS) stimulant. It is in the methylxanthine class. It is found in many plants, and is used in drinks like coffee, some teas, some soft drinks, and energy drinks. It can be harmful for both humans and animals if a large amount is consumed. If a person ate 10-13 grams of caffeine quickly, between 80 and 100 cups of coffee, they would overdose and may die. It is the world's most popular psychoactive drug, and is legal in nearly all of the world.