Hammer projection is suited for thematic maps of the world, such as land cover.
The central meridian is half as long as the Equator and a straight line. Others are curved and concave toward the central meridian and unequally spaced.
With the exception of the Equator, all parallels are complex curves that have a concave shape toward the nearest pole.
Only the Equator and central meridian are straight lines.
Scale lessens along the Equator and central meridian as proximity to the origin grows.
World maps only.
Source: Snyder and Voxland, 1989