* Defining "language" is complex: Is a dialect a language? What about sign languages? There's no universally agreed-upon definition.
* Constantly changing: Languages are constantly evolving, dying out, and emerging.
* Limited data: Many languages, especially those spoken by smaller communities, are not well documented.
However, estimates range from 6,000 to 7,000 languages.
Keep in mind that this is just an estimate, and the actual number could be higher or lower.