Dürer was a German artist who went to Italy to study the work of the Renaissance artists there. He studied perspective and the theory of proportions. He became most famous for his engraved images in metal plates via intaglio printmaking, which is a process in which ink is forced to fill lines cut into metal surface. His famous work of the Knight, Death, and the Devil is an engraving made in 1513.
The figures in this picture are reminiscent of the strange creatures in Northern Gothic paintings, as Dürer liked to combine his own ideas with Renaissance ideas. It shows a stalwart Christian soldier making his way to the heavenly Jerusalem (which we can see on the hilltop), accompanied by a loyal dog. Death is the scary old man holding up the hourglass (indicating that his time is running out), and the Devil is a weird, almost silly-looking animal-like thing (Dürer here makes fun of Satan).
Dürer also made woodcuts—prints made from a design raised in relief on a wooden block. The Four Horsemen of the Apocalypse is a woodcut which he engraved.
This image was inspired by Revelation 6:1-8, where the Apostle John describes four horsemen to come during the End Times. (From closest to farthest in the engraving I list them). The rider on a sickly, pale horse is death; the rider holding a set of scales (weights) on a black horse is plague and famine; the rider carrying a sword on a red horse is war; the rider on a white horse is conquest (though Dürer makes a mistake in that in the biblical account the rider has a bow but no arrow).