Usually, the weed or marijuana is derived from cannabis plant and the specific type of weed has been identified based the type of cannabis plant and the way the plant has been prepared. There are two types of main or active ingredients are there in marijuana, one is THC (tetrahydrocannabinol) and the other one is CBD (cannabidiol). THC helps to alter your moods swings and cognitive functioning because this active ingredient is highly based on psychoactive effects. CBD is totally different from THC because CBD helps to feel relaxed by ignoring the heavy pain in your body. As both are used for medical purposes but the effect may vary. According to the doctor’s advice you can buy weed online.