An outpost is a port where you can put your ships in dock, store your items in the warehouse, and teleport to other outposts.
The outpost should be your base of operations in the area.
On PvP servers it is recommended they be in a Free Town (since free towns can't be captured)or another port that is designated as unconquerable.
The warehouse in the outpost has limited space and you can expand it for 50k if needed, a much cheaper way is to leave one trader snow permanently in dock and you are able to store up to 3200 kg of weight in it for as long a you need it.
You can initially dock up to 5 ships per outpost however you can have up to 6 in an outpost at one time if you are in one of those 6, Redeemables can only be redeemed in outpost ports.
You can build up to 5 production buildings but they must all be in outpost ports.
In an outpost you can teleport to any other of your outposts with only your gold and upgrades - no ships.