The best description of the term "drug withdrawal" is that it is the physical and psychological response that occurs when a person stops or significantly reduces the use of a drug on which they have become dependent. This response can include a range of symptoms such as anxiety, muscle pain, insomnia, sweating, nausea, mood swings, and cravings. Drug withdrawal happens because the body has adapted to the presence of the substance and struggles to regain balance when the substance is removed. It involves both physical and psychological dependence developed through prolonged use and can have varying severity depending on the substance and individual circumstances.