This page sums up a large amount of questions, along with accurate answers. If you cannot find your problem on this page, or here (if it's a survival-related question), feel free to ask around on the forums.
A: To use a custom skin you must first purchase the game. You can then go to your profile page on the Minecraft website, download the reference skin, edit it to your liking and finally upload your customized skin also at the preferences page. You should now appear with your new look whenever you play. You need to log into your account for it to show. However, if you often play single player offline and find yourself uncomfortable because you are wearing the default skin, you can use a compression archive manager such as 7zip or WinRAR to extract the file named "minecraft.jar" (the location of this file can be found using the "options" button on the Minecraft launcher), enter the sub-folder "mob", and directly edit the picture "char.png" using your favorite image editing program. Be sure to keep the picture the same size, name, and location as it was when you first opened it, or else Minecraft may not recognize it and will not run correctly. Although this method causes your character to wear your custom skin all of the time, other people on multiplayer servers may not see your skin because they are not using the "minecraft.jar" in which you changed the default player skin. To ensure maximum over-all visibility of your custom skin, one might recommend that you go through both processes mentioned in this paragraph. However, the second process mentioned in this paragraph will probably not work for Minecraft Classic.
Q: Can the water level change?
A: Yes. In the full game water can be picked up with a bucket and placed in other locations to form a spring. Water will drain downwards and outwards when filling spaces adjacent to the spring and the flow will stop when the source block is picked up. However, the general "sea" level never changes.
In Classic the water level is set by the level of the ocean border surrounding the map, and so cannot change. Water will fill any adjacent empty space and even a single water block acts as an infinite source that is capable of flooding everything at or below its height. Some custom multiplayer servers allow players to "build" both active and static water blocks, and it is also possible to add water to your own maps by using an editor.
Q: What are the controls?
A: See Controls. The controls can be found beneath the creative mode gameplay window and are customizable from the pause menu (accessible by pressing Escape). In minecraft, the "Controls..." menu can be found in the "Options..." menu. By default, these are W=forward, A=left, S=reverse, D=right, Space=jump, Left Shift=sneak, E=inventory, T=talk/chat, Q=drop item, Esc=cancel. A two-button mouse is required for mouselook. In general, hold left mouse button to destroy blocks or punch Mobs, right-click to place blocks, activate certain blocks, or eat food.
Q: How can I drop a stack of items?
A: You can drop a complete stack of items by picking it up in the inventory screen and then closing the inventory screen. The stack of items you were holding will be dropped. You can also grab a stack and click with it outside the inventory window to throw it.As of 1.4.6, pressing Ctrl+Q throws a stack of items.
As of Beta 1.0, leaving items in the inventory's or the crafting table'scrafting square will cause them to be dropped when the inventory is closed.
Q: How do I save and reload my position (spawn point)?
A: In the full game, the spawn location is where you start out at the beginning of a map and you will return there if you are killed. This spawn point can be changed by sleeping in a Bed. There are also unofficial mods in which you can change the spawn point.
In Classic your spawn location starts out as the default that the admin set. This can then be changed by pressing Enter, saving your current location so that you will respawn there when R is pressed.
Q: How do you make plants grow? They keep disappearing on me.
A: This depends on the plant's needs for its surroundings and the light level. Grass only grows on dirt and needs light level of 4 or higher to spread (see its requirements for more details). Mushrooms, however, will only spread onto solid blocks with a light level lower than 12 (see mushroom farming for more details). Before 1.1, wheat could be destroyed by walking on it, this includes the player and mobs, but could be prevented by sneaking.
Q: Why does my building collapse / get destroyed on its own?
A:Sand and gravelblocks are subject to gravity. A sand or gravel block that has no blocks underneath it will fall until hits another solid block.
Wood, wooden planks, and many other materials are flammable, and may be set on fire if placed near fire or lava, or lit by Flint and Steel. Other possible causes of a missing or damaged house could be Endermen carrying away the blocks of your house (If made of blocks that an Enderman can carry) or explosions caused by a creeper or TNT. If you are playing on multiplayer, your house could have been griefed.
Q: Are the blocks affected by gravity?
A:Sand, Gravel, Anvils and Dragon Eggs will fall into empty space directly underneath them. TNT is subject to gravity only when primed. All other blocks — dirt, stone, glass, etc. — are not affected by gravity.
Q: Do the small plants grow into full trees?
A: None of the plants naturally present do, but if you plant saplings in a lit area with enough space above them, they will grow into small or large trees if given time. You can also use bonemeal to make them grow instantly.
Q: How do I play an external map in Survival Mode?
A: You must place the folder containing your map in one of the following folders:
A: You can play Minecraft in astounding 3D-o-scope by turning this option on and wearing red-cyan 3D glasses. However, you can't use cinema 3D glasses.
The clouds will be glitched and appear to be in the foreground with Fancy graphics.
The first person view of the item currently held will appear to be doubled, overlapping each other.
Minecraft does not support any other kind of 3D display yet. Old nVidia 3D drivers which support OpenGL may work.
Q: Who is this Notch guy I keep hearing about?
A:Notch is the creator of Minecraft, as well as its developer. He was a Lead Developer for a long time. This was changed on December 2, 2011, he stepped down and gave Jeb the job of Lead Developer. He stated that he will not work on Minecraft any longer as he is testing new coding skills on making different games.
