Cell injury refers to the damage that occurs to cells due to various harmful stimuli, such as toxins, infections, or lack of oxygen. This damage can disrupt normal cell function and lead to cell death if the injury is severe or prolonged. Common types of cell injury include necrosis, where cells die in an uncontrolled manner, and apoptosis, which is a programmed and controlled form of cell death. The response of cells to injury can vary based on the type and severity of the damage. Mild injury may lead to reversible changes, allowing cells to recover, while severe injury can result in irreversible damage. Understanding cell injury is crucial in fields like pathology and medicine, as it helps in diagnosing diseases and developing treatments.