Crystal meth is a highly addictive stimulant that people use for its intense euphoric effects. It works by flooding the brain with dopamine, overwhelming the brain's pleasure and reward systems. Short term effects include increased energy and alertness but also irritability and paranoia. Long term use can lead to serious health issues like anxiety, psychosis, and brain damage. The document provides an overview of what crystal meth is, why people use it, and its various short and long term physical and psychological effects.