Minecraft wiki entry for Tips_and_tricks, associated text: All these tools have "durability", meaning that they can only mine a limited number of blocks. When they run out completely, the tool will break, leaving you bare-handed. The decreasing durability is shown by a little colored bar under the tool (no bar means that the tool is unused, with full durability). In desktop editions of Minecraft, pressing F3 + H will change the display mode so that their tooltips show the numeric value of the durability. As the game progresses, you will be able to enchant tools to extend their durability and even let them repair themselves as you gain experience.