There are perhaps three hundred sign languages in use around the world today. The number is not known with any confidence; new sign languages emerge frequently through creolization and de novo (and occasionally through language planning). In some countries, such as Sri Lanka and Tanzania, each school for the deaf may have a separate language, known only to its students and sometimes denied by the school; on the other hand, countries may share sign languages, although sometimes under different names (Croatian and Serbian, Indian and Pakistani). Deaf sign languages also arise outside educational institutions, especially in village communities with high levels of congenital deafness, but there are significant sign languages developed for the hearing as well, such as the speech-taboo languages used in aboriginal Australia. Scholars are doing field surveys to identify the world's sign languages.

The following list is grouped into three sections :

• Deaf sign languages, which are the preferred languages of Deaf communities around the world; these include village sign languages, shared with the hearing community, and Deaf-community sign languages
• Auxiliary sign languages, which are not native languages but sign systems of varying complexity, used alongside spoken languages. Simple gestures are not included, as they do not constitute language.
• Signed modes of spoken languages, also known as manually coded languages, which are bridges between signed and spoken languages

The list of deaf sign languages is sorted regionally and alphabetically, and such groupings should not be taken to imply any genetic relationships between these languages (see List of language families).