Storage
The Self Storage is a place to safely store any items or ore you have collected. Every miner has one! It's a perk of living in this town.
Many items are useful later in the game, so you can store whatever you don't feel like selling.
The Self Storage is a marvel of Dwarwven magical engieering, and it has unlimited space, so don't worry about putting too many items in there. When you deposit more than 20 different types of items, the slots will expand to give you more room for more items.
Certain items that are especially important to progressing in the game may be automatically sent to your Storage Locker when you drop them. You may also find if you drop other items in town that they are sent to the Storage Locker automatically, thanks to the town's anti-littering laws.
If you like collecting achievements, filling the storage locker as full as you can with a veriety of items will help you towards your Pack Rat achievements.
They say the Self Storage was built by dwarves, but no one really knows how it works.