A generic language where speech is achieved by hand gestures rather than sound. There are many different languages, usually one per country, with many dialects within each country. Sign languages are usually developed organically, largely by the deaf community. There is, however, an International Sign Language that is similar to Esperanto in idea, and was specifically created.

While sign languages are used primarily by the deaf community, in fact they are useful for anybody, when speech cannot be relied upon (because of loud background noise or similar).

For further examples, see American Sign Language and British Sign Language.