Cannabis is usually smoked, either in cigarette form or using a pipe. It can also be consumed orally, either by brewing it in tea or by cooking it in food.
Cannabis contains the active ingredient THC (tetrahydrocannabinol), a chemical similar to one produced naturally by the brain.
THC affects the areas of the brain that influence pleasure, memory, movement, concentration and coordination. It can also have an effect on the functioning of the nervous system.