Engagement
Leaderboard
A ranked list of members by XP, messages or another activity metric, usually available as a command and a web page. The visible half of a levelling system.
Leaderboards matter more than they look: they are the feedback loop that makes a levelling system produce behaviour rather than just accumulate numbers. A leaderboard nobody can see does very little.
The design question is the window. An all-time leaderboard calcifies — the same names sit at the top for years and newer members disengage. A rolling weekly or monthly board stays winnable.