* Defining a dialect is subjective: There's no universally agreed-upon definition of what constitutes a dialect. Some consider dialects to be regional variations of a language, while others might include social or even individual variations.
* Continuum of variation: Language variation exists on a spectrum. It's often difficult to draw clear lines between dialects, especially where languages are closely related or have a long history of contact.
* Lack of comprehensive data: There's no global database of all dialects. Many languages, especially those spoken by smaller communities, are poorly documented.
Estimates:
* Some estimates suggest there might be tens of thousands of dialects spoken worldwide.
* Others suggest that there might be hundreds of thousands.
Important Note: Even with an estimated number, it's crucial to remember that dialect variation is a dynamic and ongoing process. New dialects emerge, others decline, and the boundaries between them can shift over time.