A firecracker is a small explosive device that makes a loud bang when lit. Firecrackers contain gunpowder packed tightly inside a paper tube with a fuse sticking out. When you light the fuse, it burns down to the powder, causing a sharp crack or pop that can startle anyone nearby.

People have been setting off firecrackers for celebrations for over a thousand years, starting in ancient China. Today, they're common during Fourth of July celebrations, New Year's Eve, and other festivals around the world. The noise is meant to add excitement to the occasion, though in some places firecrackers are illegal because they can cause injuries or fires if handled carelessly.

The word also describes someone with a lively, energetic personality. If your friend is full of energy and excitement, always bouncing around with new ideas, someone might call her a real firecracker. Like the explosive device, a person described as a firecracker tends to be spirited and impossible to ignore, bringing energy and spark to whatever they do.