Basically they're platelets and dried blood. The medical term of what a scab actually is would have to be a clot because that's what your skin's doing to heal properly. it's definitely not recommended to pick at the scab or anything because it CAN scar. Although another way scar tissue can appear is if your skin is too damaged to heal all the way.
i hope all is well, and i helped! good luck, rockstar! (: