Question

What do we call waves that must travel through a medium?

Answer 1

I found this on Google. You could have done the same and gotten your answer much faster than two hours.
"Waves that transfer energy through a medium are called mechanical waves. Waves that can transfer energy through a vacuum and do not need a medium are electromagnetic waves. Electromagnetic waves are produced by the vibrating charged particles, resulting in changes in electric and magnetic elds.Apr 21, 2020"

Answer 2

thanks bob