How many joints are in the human body?

There is no definitive answer to this question. The first problem is that the number of bones in a body changes. A fetus has about 300 bones, but by the time of birth, many of them have fused together. The average adult human has 206 bones.

Also, what constitutes a "joint" is problematic. The skull is made up of a number of bony plates that knit together along their edges into a permanently fused structure that we think of as a single unit. Do we count each of those plates and where they meet each distinct other plate as a "joint"? Consequently, there is no simple or reliable answer to this question.

The number is certainly in the range of the mid-200s to the mid-300s.