A massive cyber attack has infected a number of organisations around the world.
There have been reports of infections in as many as 74 countries, including several in New Zealand.
Computers in have been locked by a programme, WannaCry, that demands $300 ($NZD430) in Bitcoin currency.
Computer hacking is when someone breaks into a computer system illegally. A cyber attack is when computer systems are deliberately damaged or disrupted by people.
The UK’s National Health Service was among organisations hit by the outbreak.
Hospitals and doctors’ surgeries in parts of England have been forced to turn away patients and cancel appointments.
Internet companies in New Zealand have said they are aware of the ransomware attacks and have taken measures to protect its systems.