Overview & Obtaining
Parkas are large, thick jackets which are used to protect one from the bitter coldness of Boreal Forests, freezing Tundras, and perilous Ice Sheets. They insulate exceptionally well, reducing the minimal comfortable temperature of the wearer by an amount that depends on material and item quality.
Parkas can be purchased from traders, crafted, or stripped from Outlanders, Pirates, or Tribals - this being the only garment that can be found worn by all existing human factions. When starting a tribal faction, there's a chance one of your starting tribespeople will spawn with a cloth parka equipped.
As a complicated garment, Parkas can only be made at tailoring benches, which requires complex clothing to be researched in order to be constructed. A parka requires 80 of any textile, and 334 seconds of work (20,000 ticks) to be created, assuming baseline global work speed, consciousness, sight, and manipulation.
Conclusion & Comparison
Parkas are the most insulating garment in the game. It's typically advisable to have parkas early-game in colder biomes. Parkas are typically influential in surviving those frozen ice sheets, tundras, and even exceptional boreal forests.
Parkas also offer the least amount of damage protection out of the 3 available coats.
The following table(s) will display how good a normal quality Parka is at insulating when made from various materials...