Material Requirement Planning (MRP) is a software-based production planning system used to manage manufacturing processes and inventory. It involves forecasting demand, creating a master production schedule, bills of materials, and using an inventory status file to determine net material requirements. The system generates reports and orders to meet requirements while maintaining low inventory levels. Distribution Requirements Planning (DRP) applies MRP principles to distribution by linking customer demand and forecasts to inventory replenishment plans across multiple warehouse locations in the supply chain.