The ability to communicate is one of the most essential capacities that an individual needs in order to fully participate in and contribute to human society. Communication allows humans to meet their basic needs by requesting assistance from another, and it also provides the means through which to develop and sustain relationships with others, perform well in school, and engage successfully in the workplace. Although many species are able to communicate—for example, a dog may bark at the door to be let in from the rain—the ability to use language and speech for the purpose of communication differentiates humans from all other species. Language and speech are complex systems used for the purpose of communication; therefore, this entry includes a brief overview of the language ...