Great People Levels

[Qwertqwert]

When you look at the great people, under movement I have Level, what does the level do?

[OssomTossom]

Isn't it just some kind of requirement that all units must have a level?

[Solver]

It doesn't really mean anything for non-combat units. For combat units, they raise a level with each promotion. 2 XP = level 2, 5 XP = lvl 3, 10 XP = lvl 4, and so on. Non-combat units gain no promotions, so their level is always 1.