EEG refers to electroencephalogram. This is a test to measure the electrical activity of the brain. During the test special sensors or electrodes are used to pick up electrical activity from the brain and analyze it. The sensors are very sensitive and are connected with a conductive gel so that they can pick up all the electrical activity. EEG can be used to diagnose any condition that causes a change in the normal electrical activity of the brain like a seizure.
EEGs are used to diagnose epilepsy, check for dementia, see if a person in a coma still has a functioning brain and study other disorders. It is used after brain surgery to see how the patient is recovering and whether there are any problems to be looked at.