Breads made with a preferment (Poolish, Biga, Sponges, Sour starter, etc) naturally tend to keep longer than others.
To keep a crusty bread's crust crisp, store in a paper bag, bread box, or cupboard. To soften a crust, keep bread in a plastic bag. If your objective is to delay staling, keep at room temperature—the temperature range in a household refrigerator stales bread fastest. If your objective is to prevent molding, refrigerate bread, since mold develops faster at room temperature.
To bring your day-old breads back to life, spray or sprinkle with a little water before reheating in a moderate-temperature oven.
Remember—old bread is not necessarily stale bread, and stale bread can be reborn as delicious breadcrumbs or crunchy croutons!