Stash
The Stash is a bigger inventory, accessible by all characters you have in the same league. The Stash is located in each of the game's towns.
All stashes are 12x12, for a total of 144 grid spaces.
Items in the stash are separated by league, meaning a character in the standard league can't access the stash from the hardcore league and so on. Your stash on any permanent league will retain its contents, even if you have no characters on that league. (e.g. if you have 1 hardcore league character, put something in your stash, then die and are sent to standard league, making a new hardcore character will give you access to those stash items again).
When a temporary league is ended, all characters on that temporary league will be sent to their appropriate parent league, and the temporary league stash tabs will appear as remove-only so you can retrieve your items from the parent league.
The default number of stash tabs is four and more stash tabs can be bought through microtransactions. The price for each new tab is 30 credits (USD 3.00) and the maximum number of tabs is over 64,000. Purchased stash tabs are global to the account, meaning they will appear on your stash no matter what league your character is currently in.
Premium stash tabs can be colored and renamed at-will. [1]
Guild Stash tabs are shared with all members of the guild, with view/add/remove permissions as set by the Guild Leader. Guild Stash tabs are automatically Premium stash tabs that can be recolored and renamed, however they are currently unrearrangeable.