An adult human body has 206 bones.
However, a baby is born with about 270 bones.
As a child grows, some of those bones fuse together (especially in the skull and spine), which reduces the total number to 206 in adulthood.
For example:
The skull bones fuse as you grow.
Some bones in the lower spine join together.
Fun fact:
The smallest bone in the body is the stapes in the ear, and the largest bone is the femur (thigh bone