The human brain is divided into two hemispheres – left and right hemispheres. Lateralization of brain function means that there are certain mental processes that are mainly specialized to one side or the other. Most mental functions are distributed across the hemispheres but there are specific processes that are specialized to one hemisphere. For example, both sides of the brain perform functions related to language. But in most people, grammar and vocabulary are localized to the left side of the brain, while understanding the emotional content of language is a function of the right hemisphere.