The wheel is another invention so ancient that we have no way of knowing who first developed it. The oldest wheel and axle mechanism we've found was near Ljubljana, Slovenia, and dates to roughly 3100 B.C.
The wheel made the transportation of goods much faster and more efficient, especially when affixed to horse-drawn chariots and carts. However, if it had been used only for transportation, the wheel wouldn't have been as much of a world-changer as it was. In fact, a lack of quality roads limited its usefulness in this regard for thousands of years.
A wheel can be used for a lot of things other than sticking them on a cart to carry grain, though. Tens of thousands of other inventions require wheels to function, from water wheels that power mills to gears and cogs that allowed even ancient cultures to create complex machines. Cranks and pulleys need wheels to work. A huge amount of modern technology still depends on the wheel, like centrifuges used in chemistry and medical research, electric motors and combustion engines, jet engines, power plants and countless others.