EEG stands for electroencephalography. It is a non-invasive neurophysiological technique used to record the electrical activity of the brain. This is typically done by placing electrodes on the scalp, which detect and measure the electrical impulses generated by neurons (brain cells) as they communicate with each other.

EEG is used in clinical settings to diagnose and monitor various neurological conditions, such as epilepsy, sleep disorders, and brain tumors. It can help healthcare professionals assess brain function, identify abnormalities in electrical patterns, and determine the location and severity of neurological disorders.

During an EEG recording, the electrodes pick up electrical signals from the brain and transmit them to a machine called an EEG recorder, which amplifies and displays the signals as wave patterns on a computer screen or paper printout. These wave patterns, known as brainwaves, are classified into different frequency bands, such as delta, theta, alpha, beta, and gamma, each associated with different states of brain activity.