On the Official Blizzard Diablo 3 Skill Calculator (whew), there's a set of different things I can choose to be my skills. At the bottom of this page, there's a set of "Passive Skills" - with "10" "20" and "30" listed in the slots.
What do these numbers mean? Does it matter which passive skill I stick in which slot?
Those numbers are the levels that passive skills will unlock at. So, you will unlock new slots at levels 10, 20, and 30.
There are a maximum of three passive skills that can be active at any one time. Which skill you use does not matter; each slot provides the same bonuses. Be aware that not all passive skills will be available until level 60, so you can continue to mix and match which skills you want.
