Altitude

Altitude is commonly expressed as a number defining the distance in layers above the base of the game environment, which is Layer zero (0). Sea Level is recognized as Layer 63, and the top of the game environment is Layer 127. Specifically, the bottom face of the bottommost bedrock block is at Y coordinate 0. This block is said to be in Layer 0. The top face of the highest block that can be placed is at Y coordinate 127. This block is said to be in Layer 126. The player can press F3 to see what Y coordinate the player's eye is currently at, with the player's eye located 1.6 blocks above the layer the player is standing on. For example, a player standing on a shore of an ocean will see their Y coordinate as approximately 65.6.

This range of numbers can be expressed in only 8 bits, a very common limit to many programming languages and applications.

Natural resources and altitude
Landscape features are found at different altitudes, as shown in this graph:

Please note: This graph was made in previous versions of Minecraft, with some things outdated such as Clay being way more rare than it is now and simple obfuscation errors.

Beware the logarithmic scale: a slight difference in the y coordinate means a large increase in relative frequency of this block type.

See the following table for a textual description of resources by altitude and tools needed to gather them.

Other naturally occurring features appear at different altitudes such as grass, wood, flowers, mushrooms, clay, cobble, sugar cane and Obsidian, but all of these features are random and must appear in conjunction with another block and the proper environment to appear.

Trivia

 * As of Beta 1.6, solid blocks cannot be placed on layer 127. However, beds can still be placed on layer 127, making it possible to place beds at the highest possible altitude. This has also been proven to work with signs, torches and other transparent blocks.
 * When at the highest level of a map in Beta, the edges of the screen will fade to black, simulating thinning air.
 * Before Beta 1.8 Pre-release, the maximum height a player could reach through the use of blocks is at layer 130 (stand on a block at layer 127, jump), you could still make a TNT cannon blasting the player upwards to go many layers past the sky level. Similarly, falling into the Void will have the player go many blocks under the lowest layer in the map. In 1.8 and after (Creative mode), one can simply fly above layer 128 to a high limit. They can also descend below bedrock, and if flying, they could be flying just below layer 0 (In the nether, this can also be achieved, as well as above layer 127). If the player's height is below -64, they start to get hurt and die.
 * In 1.7, climbing to the top layer and jumping while carrying a block in your hand will result in the block turning black for a split second
 * Similarly, mods that allow the player to fly will allow you to go above the normal limit. When the player goes too high, the world fades from view quite rapidly, leaving them surrounded by a deeper blue, similar to the Void. If they fly downwards, or turn off the flying ability, they will fall back to the normal world (certainly dying from fall damage unless protected).
 * As of the 1.8 Pre-Release, the player's view distance decreases in lower altitudes.
 * If a Player was using mods to fly high past the block limit the game would crash

Höhe Altitude Wysokości Абсолютная высота