Skin

Skins refer to the textures that are placed onto a player or mob model.

Properties
Skins are divided into areas that act as the surface area of the character (for example, the front head area, left leg area, etc.). There are a total of 3,264 pixels that can be customized, with 1,632 on each layer. Skins with slim arms have 3,136 pixels, with 1568 pixels on each layer. The second layer can be used to give the character glasses, hats, or other accessories (even a bigger head).

$$, a skin allows only a solid color; transparency is not allowed on the skin file except on the second layer, which is transparent by default; playing offline, pixels can be left free resulting in "holes" in the skin. If a skin with transparent pixels on the first layer is uploaded, the transparent pixels render as black pixels in-game.

$$, skins can have double the resolution of a normal skin. This means the skin template can be up to 128×128 instead of just 64×64. The normal templates still apply, but players get 4× the amount of pixels to work with, since both dimensions have been doubled. Transparency can be used, even on the first layer, though there needs to be at least one visible pixel, so a fully invisible skin can't be made. The transparency must also be 0% or 100% as translucent colors are not allowed in either layer. Pixel size of the 2nd layer on body, arms and legs is 0.25 pixel bigger than the skin pixel (inner layer). For head 2nd layer (Hat layer) it is 0.5 pixels bigger than the skin layer (inner layer).

World textures
A skin can also refer to other textures in the game, such as block textures, item sprites, mob skins, etc. A list of these can be found here.

It is worth noting that a zombie and its variants can use typical player skins (and vice-versa). Skeleton mobs can use typical player skins as well, but keep in mind that they have their skinny arms and legs. If a skeleton mob skin is used as a player's skin, their legs and arms do not appear skinny.

In order to use the player skin for zombies, the user must align it to the correct place on the to avoid a visual break in the texture.

Java Edition
Only players who have purchased Minecraft can change their character's skin. This is done on the profile page or in the Minecraft Launcher by uploading a valid texture that is 64×64 pixels, or a legacy texture that is 64×32 pixels, which then replaces the default skin.

Skins also have the option of having either 3 or 4 pixel wide arms, which can be changed on the profile page as well.

The and  files in client.jar can also be changed and replaced via a resource pack, but the effects are visible only to players using the resource pack, and affects all players with the default skin.

Other versions of Steve and Alex in officially-released skin packs and other Minecraft media exist:

Bedrock Edition
Since Pocket Edition v0.11.0 alpha, players can choose one of the two default skins either Steve or Alex, and can apply their own custom skin. (Uses the same format as the Java edition). The player must select a valid skin image from their photo library, and must choose between the two main models. Players can also spend Minecraft Coins to buy skin packs. The Legacy Skin Pack was also implemented $$, but the player has to sign in to Xbox Live to access all the skins. It also includes five anonymous skins. Players can also make their own skin packs, which must include a manifest.json file, a skins.json file, and all the desired skins. An additional .lang file can be added inside a folder labeled texts to display the skin names, but the game can register the skins without it.

Character creator
The character creator is a feature $$ (and was $$ until discontinuation) that lets players customize their skins with free and paid-for cosmetic items. It can be accessed by selecting the character profile button on the main menu. It can also be used to equip capes. Many clothing items cost Minecoins (Tokens on PlayStation 4), or can be earned by completing certain achievements.

Skin packs
Skin Packs are available $$ as downloadable content. They can be aquired:
 * through the Marketplace. Most of them cost Minecoins (Tokens on PS4), but some have been released for free.
 * through files put in the  or  folder in the game files (accessible only on Windows 10, Android, iOS, iPadOS, and Fire devices).

Java Edition Skin Packs
The following skin packs were released on minecraft.net by Mojang Studios for certain events.

There might be more Java Edition exclusive skin packs released by Mojang Studios not yet listed in this table.

Templates
Many players prefer their own unique skin. While many premade skins can be found online, many players prefer to create their own.

A custom skin is a way to personalize the player model and can be done either by using a variety of community-made skin editors, or by editing the or  file manually with an image editor like Photoshop, GIMP, Paint.net or similar image editors. The file can be downloaded here and the  file here. When editing the or  file manually, be sure to keep the original image dimensions and make the background of the skin (the unused pixels) completely transparent. Otherwise, Minecraft may fail to recognize the skin as intended.

Alternatively, some may find it easier to use a program, either downloadable or in-browser, which provides a live view of their character on a three-dimensional model as they are editing the skin. For example, programs may further assist players by providing them with a wide variety of pre-made selections (such as hats, boots, sweaters, etc.), to give the skin creator exactly what they want, even if the creator has little to no artistic skill.

After making a custom skin, either by using a skin editor or by editing the file directly, one still needs to upload the  file at the Skin section of the Profile page on Minecraft.net (found here) before the skin is applied. Other players in multiplayer can also see this skin. Note that players cannot see the custom skin if they are not logged in or when playing offline.

Official skin templates
Minecraft Help Center Article

Other templates
To 6 significant figures, there are 3.06013×1023,581 possible unique Minecraft skins.

Trivia

 * There are about 9.571 656 652 × 1031441 possible skins in, with 5.412 073 956 × 1027511 compatible online.