Breadcrumbs are the small pieces of dried, crumbled bread used in cooking. Cooks press breadcrumbs onto chicken or fish before frying to create a crispy, golden coating. They also mix breadcrumbs into meatballs or meatloaf to help hold everything together, and sprinkle them on top of casseroles for a crunchy finish.

Today, breadcrumb trail means any series of clues or markers that help you trace your way back or follow a path. When you're on a website, you might see breadcrumbs at the top of the page showing “Home > Books > Mystery > Sherlock Holmes,” which tells you exactly where you are and lets you click back to any earlier section.

The metaphor works in other ways too. A detective following breadcrumbs of evidence is piecing together small clues that lead toward solving a mystery. When someone leaves you a breadcrumb trail of hints about what they want for their birthday, they're dropping little clues for you to follow.