Charcoal is a black, crumbly material made by heating wood in a place with very little air. When wood burns normally, it turns to ash, but when it's heated slowly without much oxygen, it becomes charcoal: almost pure carbon that burns much hotter and longer than regular wood.

People have made charcoal for thousands of years because it's incredibly useful. Blacksmiths use it to heat metal hot enough to bend and shape into tools. Artists use thin sticks of charcoal for drawing because it creates rich, dark lines that can be smudged and blended. Many families use charcoal briquettes (pressed blocks of charcoal) for grilling burgers and hot dogs because charcoal burns steadily and gives food a distinctive smoky flavor.

Charcoal also appears in another surprising place: some water filters use activated charcoal, which has been treated to make it incredibly porous and able to trap impurities. The same substance that helps cook your dinner can also help clean your drinking water.

As an adjective, the word can describe a dark gray color, like a charcoal suit or charcoal clouds before a storm.