Definitions:
Haven: a ‘safe area’ the party is unlikely to encounter combat, such as settlement (village, town or city) populated by non-hostile NPCs, or a hidden place in the wild.
Rest areas:
Inns, free beds and potentially even your own base are considered ‘rest areas’. For Inns specifically you will be charged money for your stay, depending on the inn quality.
Wilderness: anywhere outside populated areas on the hex map.
Rules:
Short rests:
Short rests last a minimum of 1 hour. A short rest costs 10 supplies. While travelling the wilderness or generally outside of a haven you may only take 2 short rests per long rest. While inside a haven you may short rest as many times as you wish (at a cost of 10 supplies) and your wilderness limit is reset upon entering a haven. While inside a rest area you may short rest freely at no cost.
Long rests:
Long rests last a minmum of 24 hours, or until the following morning after 24 hours. A long rest costs 50 supplies.
While travelling the wilderness or generally outside of a haven you must have a bedroll, a tent or a shelter, and a method to create a camp fire.
While inside a rest area you may long rest freely at no cost.