An electroencephalogram, or EEG, is a test that measures electrical activity in the brain. It involves placing small electrodes on the scalp, which detect and record brain waves. This information helps doctors understand brain function and diagnose conditions like epilepsy, sleep disorders, and other neurological issues. EEGs are non-invasive and typically take about 20 to 40 minutes to complete. Patients may be asked to relax, sleep, or perform specific tasks during the test. The results are analyzed by a neurologist, who interprets the patterns of brain activity to provide insights into the patient's health.