What are some ways to find "Minecraft" block numbers?

Minecraft Info provides a comprehensive list of the ID numbers and ID names of all of the items in Minecraft, including blocks, food and potions. Minecraft Data Values is another free online research site where the identification numbers of Minecraft blocks can be found.

Blocks and other entities in Minecraft are identified by the game using a specific number corresponding to each item, as well as a name in certain versions of the game. Minecraft players can use these numbers in conjunction with in-game commands to add, delete or edit blocks in their world. Minecraftopia also provides these ID numbers as well as information on how to use game commands.