What years constitute the medieval period?

The "medieval" (pronounced "MED-E-VAL, not MIDevil or MEDevil) period, also frequently called the "middle ages," is typically defined as the years 500 AD to 1400 AD. The medieval period begins with the collapse of the Roman Empire and stops with the period that begins the Reformation and the Renaissance.
The medieval period refers to literally everything that took place over that a nine hundred year span, including all works written and created.