What is the function of an overhead valve engine?

OHV engines run with the camshaft built into the cylinder block, unlike SV engines (no longer used) where they run parallel to the cylinder block. More commonly used in the modern world are OHC (overhead camshaft) engines, which run in a similar manner to OHV engines, eliminate the need for pushrods.

The function however? Is the same as any other engine; to spin an axle with high RPM/Torque depending on application.