With languages, then, it is much the same.
The society or group of poeple who use the same language, i.e. the same convention, make up a speech community. The members of such a speech community can now communicate among themselves, because they have agreed to use the same convention, that means the same form of phonetic realization, which leads to a direct association with the same notion.
The linguistic signs of every language are arranged in a grammatical system which is again used in this speech community as a convention. The ability to create a system out of signs is a unique capacity of human beings.
The number of languages spoken in the world today is estimated at more than four thousand. Comparative studies of these lqnguages reveal that they may be classified into several language families, each of which contains from 2 to 100 or more separate but related languages.
Languages so related are said to have diverged from a single ancestoral tongue, called a protolanguage, that is now no longer spoken and for which records are not available. The large number of unrelated language families points up the great diversity of modern tongues and suggests that language developed very early in man´s pre- history.