Container

Container is a general term for any item or object that can be looted or can store other items.

Examples of containers:

Any of various bag items that a player character can carry.
Any footlocker, sack, lockbox, etc. object that can be right-clicked (gear pointer) to open and loot.
Any of various chest objects that can be found around the world and looted. Some may be locked.
The water tub objects that appear on the ground during the Hallow's End event, which are looted for water to put out fires.
The water bucket item that appears in your inventory when you loot the water tub.
The Brewfest Festive Keg objects that appear on the ground during the Brewfest event, which are looted for a sample of Brewfest brew.
The [Blue Brewfest Stein] and the [Yellow Brewfest Stein] which hold the brew when you loot the keg.

Note that some conceptual items in the game are represented primarily by their container.

Other than by the containers, the water used to put out the fires during Hallow's End is only shown as a brief splash animation when you throw it, and by the gradual effect of putting out the fire.
Other than by the containers, the beer you loot from the kegs and drink from your Stein is only shown by effect when you are drunk, or as a health bar when the Brewfest Festive Keg is attacked by Dark Iron Dwarves.

Pointers for opening:

in range to open

out of range