Brain activity refers to the electrical and metabolic processes that occur within the brain, which are responsible for cognition, emotion, movement, and sensory perception. It involves the firing of neurons, the release of neurotransmitters, and the overall functioning of the nervous system. Brain activity can be measured through various techniques such as electroencephalography (EEG), which records electrical signals from the brain's surface; magnetoencephalography (MEG), which measures magnetic fields produced by electrical activity in the brain; or functional MRI (fMRI), which detects changes in blood flow related to brain activity. Understanding and analyzing brain activity is crucial for researchers studying neurological disorders, as well as for those interested in understanding human behavior and cognition.