The Dark Ages in Western Europe began when the Western Roman Empire fell and lasted all the way until the beginning of the Renaissance. The last emperor in Rome left his throne in A.D. 476, although the empire had been on a downward slope for a long time beforehand. Setting a precise date for the start of the Renaissance is challenging, although it was well underway by 1300.
The term "Dark Ages" was not applied to this point in history until the 1800s, when historians such as Edward Gibbon looked back fondly at the level of civilization at work in the Roman Empire and deplored the brutality and dearth of intellectual enterprise at work in the centuries after the collapse. Because of a lack of civilization to provide light, Europe instead fell into a morass of dominance by the Church and the system of feudalism.
However, several historical discoveries are making the term "Dark Ages" less and less relevant. Such discoveries as the intellectual treasures that were stored in monasteries and innovations in technology and art that were taking place as early as the 900s meant that this time period may not have been as hopeless as many historians have thought.