There are many different types of inventory slots in MapleStory 2, and many actions that can be performed from within your inventory itself.
There are 12 different inventory tabs for MapleStory 2:
Gear - For armor, accessories, and weapons that can be equipped.
Outfits - Cosmetic items and fashion pieces are located here.
Mounts - Store your ride-able cars, trucks, birds, and paper airplanes.
Catalysts - Materials for enchanting are stored in tn this inventory.
Life Skills - Materials gathered from Farming, Foraging, Mining, or Ranching.
Fishing / Music - Hold your fishing poles, instruments, and music scores.
Quest - Items gathered and used for quests.
Gemstones - Gems and Gem Dust for socketed items.
Pets - A safe storage for the critters that you have obtained.
Consumables - Potions, elixirs, and temporary character buffs.
Currency - Various currencies, such as event Kay Coins, and Guild Coins.
Badges - Contains items that change the appearance of your name tag or chat bubble.
Misc - Random reward boxes and other items.
From your inventory you can also Enchant Items, Change Bonus Attributes, Dismantle, Socket Gemstones, and Lock items. There are even buttons to change Auto-loot settings, and to organize your inventory.