In this paper, SCADA system and cyber security is discussed. Transportation, chemical, water, natural gas, petroleum, electricity, and energy sectors rely heavily on the ability of Supervisory Control and Data Acquisition (SCADA) systems to monitor and respond to changes and fluctuations within the system (NIPP, 2009). Changes can be reflected by natural elements such as the weather or based on customer demand. SCADA refers to the computer controlled and interfaced systems that run an industry's operations. SCADA systems at one time were not connected to the outside world and industrial operations were computer controlled within the property boundary that defined the facility. This also increases risk of cyber threat. In this paper, we will discuss SCADA usage and cyber vulnerability.