Morphology studies the internal structure of words and their alteration through the combination of morphemes. A morpheme is the smallest element in a language capable of creating a distinction in meaning. There are bound morphemes (e.g. -s, -ed, -ing) and free morphemes (e.g. go, stop, run).
Syntax refers to the rules that govern how words combine to create meaningful utterances. Morphemes combine to form words, words combine into phrases and phrases combine according to set rules into clauses.
Semantics is the study of the meaning of linguistic tokens such as words, phrases and clauses. It examines which signs are used, how they make reference to things, ideas, emotions, and so on, and how the hearer interprets them.
Brain scanning has been used to demonstrate specialization within language areas in the brain – notably in Broca’s area. Brain scanning of normal brains appears to support the findings of studies of language processing in people with aphasia.
Aphasia is caused by localized brain damage, for example due to a stroke or an automobile accident. General intellectual functioning is not necessarily impaired, as the person can still perform non-linguistic tasks. Nor is the understanding and production of language necessarily completely abolished. Instead, there are highly specific patterns of impairment in the way language is processed.
Humans possess a general language capacity that allows them to speak particular world languages. Language is highly complex but can be defined in terms of a number of key properties.