Zero-based budgeting (ZBB) is a budgeting approach where every expense must be justified from scratch, regardless of previous budget allocations. Unlike traditional budgeting methods that rely on incremental changes, ZBB requires all expenses to start at zero and be justified based on their necessity and value. Each budget item is evaluated based on its merits, and resources are allocated based on the needs and priorities of the organization. ZBB promotes a thorough review of expenses, encourages cost control, and enables resource reallocation to areas that provide the highest return on investment. It promotes efficiency, accountability, and strategic allocation of resources.