Atrophy refers to the gradual decline or wasting away of a body part or tissue, often due to lack of use, injury, or disease. This process can affect muscles, organs, or even the brain, leading to reduced function and strength. Common causes include prolonged inactivity, malnutrition, or certain medical conditions. In the case of muscles, atrophy can occur when a person is immobilized, such as during recovery from surgery or injury. Regular exercise and physical therapy can help prevent or reverse atrophy by promoting muscle growth and maintaining overall health.