Supervisory control and data acquisition (SCADA) systems were developed as a way to manage large scale industry and utility in as efficient a way as possible and govern the safe use of water, gas, electricity, oil, electricity and nuclear power. They are used by power generation and distribution, oil and gas refining and distribution, water and waste systems, chemical processing and transport, manufacturing, telecommunications and even banking infrastructures. In short, just about every industry that is vital to the functioning of modern society.
Many of these systems have been around for twenty years or more. As a result, they are getting old and coming up for replacement. It makes good business sense for utilities to integrate SCADA systems with their corporate networks, so that they can administrate them more cost effectively. As a result, SCADA networks are being migrated to the all-pervasive TCP/IP Ethernet network. Herein lies the problem: SCADA has used arcane technology that only a small number of specialists have the skills to use. Hence it's hardly ever been hacked. However, every hacker in the world understands IP.