Why don't Rocket Engines melt

Why don’t rocket engines melt? How engineers keep engines cool?

Rocket engines need to produce heat to function, after all, their only real purpose is to convert the chemical energy in the propellant into pressure and heat so they can produce thrust.

And that brings up an obvious question! How in the heck do engines survive this heat? How did rocket scientists figure out how to keep an engine running continuously while harboring combustion inside it that’s hot enough to melt the very walls that are containing it?!