What are stimulants? List various stimulants and their source

Dear Student, 

Stimulants are certain type of drugs that greatly affects our central nervous system by increasing the activity of its brain. By increasing the electricsl activity in our brain, variouseffecys like fatigue can be decreased, lifts up your mood. 
Various type of stimulants are:-
1. Nicotine in tabacco.
2. Caffeine in coffee, tea.
3. Cocaine a certain type of drug obtained from coca plant.

Regards