* No centralized census: There's no global organization tracking sign language users.
* Varying definitions: "Sign language" can refer to a single language or a family of related languages.
* Diversity of sign languages: Hundreds of sign languages exist, each with its own regional variations.
* Unrecorded users: Many sign language users might not be formally registered or documented.
However, we can estimate the number of sign language users based on the prevalence of deafness:
* World Health Organization estimates: The WHO estimates that about 5% of the world's population experiences some degree of hearing loss.
* Deaf population: A significant portion of deaf individuals use sign language as their primary communication mode.
Based on these estimates, it's likely that millions of people around the world communicate using sign languages. However, this number is constantly changing and is difficult to definitively quantify.