An EEG, or electroencephalogram, is a test that measures the electrical activity of the brain. During the test, small metal discs called electrodes are placed on the scalp to detect brain wave patterns. These brain waves represent the electrical signals produced by brain cells as they communicate with each other. The EEG records this electrical activity, displaying it as wavy lines on a computer. The test is non-invasive and painless. It is commonly used to diagnose and monitor conditions affecting the brain such as epilepsy, seizures, brain inflammation, sleep disorders, head injuries, and brain tumors. By analyzing the brain waves, specialists can identify abnormalities or unusual brain activity that may indicate medical conditions. The test usually takes between 20 to 40 minutes, during which the patient may be asked to relax, open and close their eyes, or respond to stimuli like flashing lights or sounds to observe changes in brain activity. In summary, an EEG is a safe and important diagnostic tool that helps doctors understand brain function by recording its electrical activity through electrodes placed on the scalp. It is especially useful in diagnosing epilepsy and other neurological conditions.