A crumb is a tiny piece that breaks off from bread, cake, cookies, or other baked goods. When you eat a muffin at breakfast, the little bits that fall onto your plate or scatter across the table are crumbs. Toast makes especially messy crumbs that seem to get everywhere.

Crumbs happen because baked goods have a somewhat fragile structure. Even the most careful eater leaves a trail of crumbs, which is why many parents don't allow crackers or cookies in certain rooms. Birds love finding crumbs, which is why people sometimes scatter bread crumbs in parks to feed pigeons or ducks.

The word appears in the famous fairy tale “Hansel and Gretel,” where the children drop bread crumbs to mark their path through the forest (though the birds eat them, ruining their plan). Today, websites use something called “breadcrumbs” to show you which pages you've visited, helping you find your way back, just like the trail in the story.

People also use crumb to mean a very small amount of anything. If someone says “I don't have a crumb of evidence,” they mean they have no proof at all. A crumb of comfort means just a tiny bit of relief in an otherwise difficult situation.