Tool

Tools are items used by the player while held to perform actions faster and more efficiently, to gather materials not obtainable by hand, to gain information, or to perform completely new actions. With the exception of the clock, compass and bucket (when empty), tools do not stack in the inventory. Tools can be repaired; see Item Repair.

Mobs
Some tools can be obtained by killing mobs that carry the equipment.

Crafting
All tools can be obtained through crafting.

Best tools
Many blocks have a preferred tool to break them. Some blocks can only be broken with certain tools. The tool's material also affects how fast a block is mined. Materials from worst to best in terms of mining speed are: wooden, stone, iron, diamond, gold.

Item durability
Different tools have different amounts of durability. Some uses require more durability to be used than others. A tool's durability is also affected by its material. Materials from worst to best in terms of durability are: gold, wooden, stone, iron, diamond.

Some tools are not block-breaking tools: This includes hoes, bows, fishing rods, carrots on sticks, flint & steel, and buckets. Such tools are no better than bare fists at breaking blocks, but they do not take damage from doing so—they only take damage by being used in their own various manners.

Item enchantability
Materials from worst to best in terms of enchantability are: diamond, stone, iron, wooden, gold.

Trivia

 * Gold tools are actually ranked as superior to diamond tools on the Legacy Console Edition's crafting screen.
 * Wooden tools can be burned in a furnace regardless of its durability; this means the player can burn a wooden tool that has only 1 use left.