Marijuana is a chemical that comes from the cannabis plant. Marijuana is bad from your health and also its dependency factor. People who use marijuana often like the effect that they get from it and so it becomes an addiction. Taking regular cannabis can cause pyschotic illnesses like schizophrenia. It can also cause problems with your day to day tasks because you have become so relaxed that you start to let things slip. You may become withdrawn and there is always the risk that you could in later life develop mental health issues.