In computer systems a loader is the part of an operating system that is responsible for loading programs and libraries. It is one of the essential stages in the process of starting a program, as it places programs into memory and prepares them for execution.Loaders typically work in warehouses, where they prepare outgoing shipments and receive incoming goods by loading and unloading trucks, trailers and shipping containers. When a vehicle arrives or departs the warehouse with freight, a loader checks route schedules and orders for accuracy.