Clothing can use to design your character, and also offer various benefits when worn (unlike hair styles or other customizations).
As your character gets tired, your shirt/pants will start to look torn up; once you rest your clothing will repair itself.
When outfitting a character there will be 2 rows of 4 slots. The top row shows the items that are being used for stats, and by default are shown on your character. The second row shows which items your character visually wear, but do not affect stats. Note that you should upgrade to the exceptional quality the clothes that you want to wear visually.
It is possible to try out different styles for your character out-of-game by using unofficial dressing rooms:
Leveling up - All tier 1 clothing can be obtained through level up rewards.
Research projects - All tier 1 and tier 2 clothing can be obtained through researching.
Loot / Drops (themed) - Every infected may drop the clothing that it wears.
Loot / Drops (non-themed) - You can find any clothing commonly in secret passages or as drops from bosses and Peruvian infecteds.
Loot / Drops (non-themed, rare) - All clothing can be found in containers or from normal infected drops, albeit very rare. The Collectioner Strategy can help with this.
You can also find survivor equipment on maps, although these behaves differently than normal clothing.
All clothing starts off in "poor" condition, except those purchased from shop - you get them at 4/5.
You may only change your outfit in "safe" zones (marked with a star on the map), such as your camp and Lakeview Lane. Additionally you can change your outfit while sitting in a fire place (placed ones included).
Clothing comes in 4 rarities/tiers that can be seen by the color of it's name in your profile / the shop. The rarity (not to be confused with how many times it's been upgraded) goes from common to rare: white, green, blue, purple (listed as 1-4 in the tables below). Unlike items that are in your backpack (or survivor equipment), clothing is not lost when you die. Effects:
The rarer clothing is, the less likely it will be dropped by an infected / found in a container (even when fighting a themed infected such as the firefighter).
When upgraded, the hp each upgrade earns you is calculated based on it's rarity.
Increases hp the item gives (higher rarity clothing gives bigger hp boosts at each stage)
A new slot becomes available (except for when they become exceptional).
Each clothing item upgraded to max quality increases your max HP by 1 (even when not worn).
In the tables below, the "Upgrade Cost" shows the amount of resources needed to upgrade 1 point towards the next quality level, which with each increasing "recipe level" progressively requiring more points:
During beta before the clothes shop was added, you obtained clothing through level up rewards; you would be given a "crate" option which once selected would open to reveal a random clothing piece you didn't have yet (with higher level clothing being rarer).
Before V1.14, "poor" quality clothing would show as torn, and had to be upgraded to at least average quality to remove torn effect.
Before V1.18 upgrades required sewing kits and varying amounts of fabric, as well as 0-2 resources which depended on the clothing.