This chapter describes the kinds of operations involved with the opening, enlarging, and finish cutting of holes ranging from a small fraction of a millimeter (µ in.) to hundreds of millimeters (in.) in diameter. In most of the operations, the tools, and not the work pieces, are revolved and fed into the material. Various types of drills, boring tools, and reamers are explained. Drilling machines are made in many forms and sizes. Portable or hand drills are well known. The drilling machines commonly used for precision metalworking are known as drill presses. Several drilling machine accessories and attachments are viewed. A variety of precision production-boring machines are available to suit the requirements for a particular set of machining operations. Drilling and boring operations are dependent upon accuracy, speeds, feeds, drilling time, costs, cutting forces, and power. Process planning can be enhanced with design for manufacturing considerations.