Never did citadel, give me the quick info

I know I get these orts from skilling, and can add them to a clan citadel, but I dont know how or why I should do it. Thanks

The avatar bonus.

When someone has the avatar out (and if you've paid 300 orts for a week of bonuses) you get an extra 3% to all the xp you gain if you're in the same world as that person. If you're within a certain range of the avatar that bonus xp become 6% I believe.

That's why if you plan to do hardcore training you should use orts.

And also if you are close enough to the avatar (22 by 22 square) you gain a set of useful buffs see wiki (click me!) for more info.