Language acquisition, how children acquire language

Language acquisition is the process by which humans acquire the capacity to perceive, produce and use words to understand and communicate. This capacity involves the picking up of diverse capacities including syntax, phonetics, and an extensive vocabulary. This language might be vocal as with speech or manual as in sign. Language acquisition usually refers to first language acquisition, which studies infants' acquisition of their native language, rather than second language acquisition, which deals with acquisition (in both children and adults) of additional languages.
The capacity to acquire and use language is a key aspect that distinguishes humans from other organisms. While many forms of animal communication exist, they have a limited range of nonsyntactically structured vocabulary tokens that lack cross cultural variation between groups.
A major concern in understanding language acquisition is how these capacities are picked up by infants from what appears to be very little input. A range of theories of language acquisition has been created in order to explain this apparent problem including innatism in which a child is born prepared in some manner with these capacities, as opposed to the other theories in which language is simply learned.