The Renaissance is not the sort of historical event that has a definite beginning and ending. Things like the Renaissance, which are characterized by the rise of certain ideas, cannot be pinpointed and given exact beginning and ending dates in the way that things like wars can be. That said, historians do have to try to assign dates to eras. They typically give dates such as 1330 to 1550 for the Italian Renaissance and 1500 to 1615 for the Northern Renaissance.
The Italian Renaissance is typically said to have begun as cities in Italy became more prosperous and more powerful. This happened in the mid-1300s. As they did so, they came to be centers of things like culture and learning. In these centers, the ideas of the Renaissance arose. The Renaissance is said to have ended as Italy lost power and foreign powers were able to invade the peninsula.
The Northern Renaissance came about as an offshoot of the Italian Renaissance. It is generally said to have begun as the Hundred Years’ War ended and Northern Europe became more stable. This brought prosperity and helped to allow the ideas of the Italian Renaissance to grow. The Northern Renaissance is said to have petered out as the ideas of the Enlightenment began to take hold.