Music Disc

Music Discs (previously named Records) are items added in Alpha that can be played in jukeboxes. They play music made by C418. It has been stated that in the future, there will be 14 music discs to find in Minecraft.

Despite the music files themselves being saved in a playable .ogg format, custom music cannot be used unless a modification is installed.

Acquiring Discs
Music Discs are dropped by creepers when they have been killed by a skeleton arrow. This can be achieved by positioning a creeper between a skeleton and yourself and having the skeleton fire on you. This method is easier if you first weaken the creeper so that the skeleton will only have to shoot the creeper once to kill it. Shooting the creeper with arrows four times, hitting it with an iron sword twice, hitting it with an stone sword three times or a hitting it with a wooden sword four times will weaken it enough that a single arrow will kill it. Music discs can also be found in chests in dungeons 8% of the time. One method of getting a Music Disc is to damage a Creeper, and trap it (and a Skeleton) in a 2x2x3 hole, then walk around the edge. Be sure to back up quickly if it hisses.

Gold Disc
The gold disc plays the track "Thirteen".
 * An ambient track consisting mostly of ambient cave noises, metallic clings, splashes, and skeleton and creeper sounds.

Green Disc
The green disc plays the track "Cat".
 * An upbeat synthetic melody.

Trivia

 * In Survival Multiplayer, when you hit a jukebox to get a music disc out of it, the music disc will pop out, as well as a ghost disc that only you can see, that you can't pick up.
 * The 14 music tracks created for records by C418 can be found in %appdata%\.minecraft\resources\streaming on Windows.
 * Of the 14, only 2 are in .ogg format (the two being Cat and 13, the current records). The rest are in .mus format, which is the format used by many music creation programs.