The word east comes from Middle English est, from Old English ēast, which itself comes from the Proto-Germanic *aus-to- or *austra- "east, toward the sunrise", from Proto-Indo-European *aus- "to shine," or "dawn". This is similar to Old High German *ōstar "to the east", Latin aurora "dawn", and Greek ēōs ἠώς. Ēostre, a Germanic goddess of dawn, might have been a personification of both dawn and the cardinal points.
By convention, the right hand side of a map is east. This convention has developed from the use of a compass, which places north at the top. However, on maps of planets such as Venus which rotate retrograde, the left hand side is east.
East is the direction toward which the Earth rotates about its axis, and therefore the general direction from which the Sun appears to rise. The practice of praying towards the East is older than Christianity, but has been adopted by this religion as the Orient was thought of as containing mankind's original home. Hence, some Christian churches have been traditionally oriented towards the east.