DCS (Distributed Control System) is a computerized control system used to control production lines in industries. It consists of field control stations with input/output modules and a CPU, an operator station for monitoring the process, and an engineering station for configuring the system. The DCS receives input signals from sensors, processes the data, and takes actions like adjusting valves based on setpoints to control physical quantities like pressure and temperature. It displays the process values, setpoints, and manipulated outputs on operator interfaces called faceplates to monitor the control process.