The principle of drying is to decrease water availability for enzymatic reactions and microbial growth by removing free water from food products. This chapter examines three dehydration techniques: tray, spray, and freeze drying and discusses the process of atmospheric drying in a tray or shelf dryer. There are major industrial methods of removing moisture from solid materials: air drying, contact drying, and vacuum drying. The chapter describes an experiment which is a batch-type operation in which food materials are evenly spaced on metal trays and placed in a drying chamber. Water loss in the product is monitored and recorded as weight loss in a digital balance weighing the trays connected to a data logger system. The minimum moisture the product can reach when exposed to a specific external medium after a theoretical infinite time is called the equilibrium moisture content.