Texture pack

A Texture Pack is a file you download in order to change the appearance, otherwise known as texture, of blocks, items and mobs. They may occasionally change the sounds. Installed textures can be changed by going to Texture Packs on the Main Menu. Since Alpha 1.2.0 Texture packs are officially supported by the game.

Installation
To install a texture pack, the file must first be obtained in a ZIP format. Then, place the file to:
 * Windows: %Appdata%\.minecraft\texturepacks

This path can be open by using the Open Texture Pack Folder link from the game client.

Texture Pack Creation
To create a custom pack the needed files must be extracted from minecraft.jar with an archiving or decompression program and edit them with any proram you like. Then zip them into archive without changing their names and folder structure

Trivia

 * Prior to the 1.2.2 update, users would need to manually change the texture packs by overwriting their minecraft.jar files.