Leaderboard

Leaderboards are a feature for Diablo III, added in Patch 2.1.

Overview
Leaderboards keep track of progress made in Greater Rifts, Seasons (and seasonal achievement points), and Conquests. Leaderboards allow players to compare their progress to that of your gameplay region, friends, and clan members. Each type of board tracks progress differently:

Greater Rift Leaderboards
Greater Rift Leaderboards are split between both Hardcore and Normal gameplay modes as well as Seasonal and Non-Seasonal characters. To help encourage a variety of play styles and allow players to measure themselves against similar competitors, Greater Rift leaderboards are broken into the following categories:

The highest rank is awarded to the player(s) who have successfully cleared the highest rank of a Greater Rift on time. Of those people, those who have completed it faster will get a higher rank.
 * Solo play for each class (e.g. top players for, Demon Hunter, Crusader, etc.)
 * 2-Player Groups
 * 3-Player Groups
 * 4-Player Groups

Season-only Leaderboards
Some Leaderboards are Season-only. For example, Conquests are only tracked on Seasonal characters, so these Leaderboards won't have a non-Season equivalent. The same is true for Seasonal achievement points. In addition, because Conquests and achievements are account-wide, their associated Leaderboards will not be split between Normal and Hardcore (even though some tasks may require playing a particular mode).