Extra Inventory

All players begin with 40 slots of inventory space.  can be acquired through purchase using in-game money, achievements, and quests, granting a player up to 104 slots of inventory.

NPC Expansion
A player is initially given an additional row of inventory after they complete the quest Inventory Trick. Players may purchase additional inventory space from an Inventory Manager or Banker. Each successive row of inventory will cost more than the previous.

Note: it's recommended to use gold to unlock inventory rows before you finish quest Inventory Trick. The quest awards one row you'd have to pay gold otherwise.

Achievements
There are two achievements that grant inventory space, each giving an additional row.
 * Level 50
 * Gathering Master

Quests
There are two quests that give additional rows of inventory.
 * Inventory Trick (usually completed before using Inventory Managers)
 * Bolstering the Home Front