Human spoken and written languages can be described as a system of symbols (sometimes known as lexemes) and the grammars (rules) by which the symbols are manipulated. The word "language" is also used to refer to common properties of languages.

Language learning is normal in human childhood. Most human languages use patterns of sound or gesture for symbols which enable communication with others around them. There are thousands of human languages, and these seem to share certain properties, even though many shared properties have exceptions.

There is no defined line between a language and a dialect, but Max Weinreich is credited as saying that a language is a dialect with an army and a navy.

Humans and computer programs have also constructed other languages, including constructed languages such as Esperanto, Ido, Interlingua, Klingon, programming languages, and various mathematical formalisms. These languages are not necessarily restricted to the properties shared by human languages.

Mass media
Mass media is a term used to denote, as a class, that section of the media specifically conceived and designed to reach a very large audience (typically at least as large as the whole population of a nation state). It was coined in the 1920s with the advent of nationwide radio networks and of mass-circulation newspapers and magazines. The mass-media audience has been viewed by some commentators as forming a mass society with special characteristics, notably atomization or lack of social connections, which render it especially susceptible to the influence of modern mass-media techniques such as advertising and propaganda.