It’s rare that I finish a full loaf of bread before it goes stale and, in those cases, I cut the left-over portions of the loaf into cubes and then leave them on a plate or baking sheet for a few days to dry out completely (Cover them with a cloth to protect them from dust). Once they’re dried, I store the cubes in an airtight container to be retrieved whenever I need bread crumbs.
Bread crumbs make everything better, especially after they’ve been sauteed in butter and then sprinkled over the top of macaroni and cheese just before it goes into the oven. Actually, they’re useful for any number of reasons. They can be used as a coating for fried foods such as arancini or fried chicken, and as thickeners and binders in a wide variety of dishes. Best of all, they’re easy to make and store.
Just throw the dried cubes into a blender or food processor, whir for a few moments until you get the consistency you want, such as fine or larger crumbs, and then you’ve got freshly made breadcrumbs whenever you need them. (If you’re looking for fine bread crumbs, sift the crumbs through a wire mesh strainer to capture the larger pieces and then run those through the food processor again.) It’s cheaper than buying bread crumbs at the store and it uses up bread that might otherwise go to waste.
Not Craig Claiborne's Kitchen Primer 