Language is the system humans use to communicate. Linguistic anthropology studies human language, and these points highlight humanity's distinct way of transmitting information:
Human infants aren't born with language already in mind, but all healthy infants are born hard-wired to acquire any of the uniquely complex rules (grammar) of any human language.
Each language has a unique grammar, a complex set of rules that tell how to properly order the words in a sentence; children normally learn the outline of this grammar by about 3 years of age.