Communication is usually understood to be the transmission of information. Many models of communication describe it in terms of a source using a coding system to express ideas in the form of a message. The message is sent through a channel to a receiver who decodes it to understand it. For verbal communication, the message is articulated in linguistic form, including regular speech and writing. Nonverbal communication, including body language, touch, and facial expressions, does not rely on a linguistic system. The history of human communication was shaped by the development of technologies such as writing