The document discusses drilling operations and drilling machines. It describes how drilling is performed using a rotating cutter called a drill. Drilling machines hold the workpiece stationary and rotate the drill to make a hole. Common types of drilling machines include portable, sensitive, radial, upright, gang, and multi-spindle machines. Drilling operations can include center hole drilling, deep hole drilling, thin material drilling, and pilot hole drilling. Safety precautions are important when using drilling machines.