The "mechanism of action" refers to the specific biochemical interaction through which a drug or substance produces its effects in the body. This includes how the drug binds to receptors, enzymes, or other cellular targets, leading to a series of biological responses. Understanding this process is crucial for developing effective medications and predicting their effects. For example, in the case of aspirin, its mechanism of action involves inhibiting the enzyme cyclooxygenase, which reduces the production of prostaglandins. These compounds are responsible for inflammation and pain, so by blocking their formation, aspirin alleviates symptoms like fever and discomfort.