Bonus Armor and MR

To expand on this, you can easily find out what is base and bonus values by hovering over the values while in game.

When you hover over AR/MR you will always see 2 values, one in blue and one in green (even if the green is 0). Blue is base, green is bonus.

Base armor is armor you champion has without item, runes, masteries. Bonus armor is armor your champion has without base armor (from item, runes, masteries, champion's passive[like shyvana]). Armor is base armor plus bonus armor.

Same for magic resistence.

+1 to this.

Base [stat name] is pretty much what your champion has form there level 0 base and per-level stats alone.

Items, runes, masteries, buffs, auras, ability steroids, ability bonuses of any kind, buffs of any kind - those are all bonus [stat name].

which you can apply to HP, AD, armor, magic resistance, and a few other stats for the purposes of abilities and items that separate bases from bonuses. Taric's Heal, Yasou's Last Breath, Trinity Force, Iceborne Gauntlet, Sheen, etc. Or even auto-attack damage against structures - which is 100% of your base AD plus the higher of 100% of your bonus AD or 40% of your total AP.

Lol i love your name ^_^