Because so much of our infrastructure including the electrical grid, water and sewage treatment, as well as our transportation system is computerized.

NPR: Cybersecurity On Display In D.C.

Other times the attacks are more personal:In 2000 a discontented consultant, rejected for a job at a water treatment plant in Australia, remotely hacked into a sewage treatment system and released 264, 000 gallons of raw sewage into rivers and parks.

FORBES: The Next Threat