Asked by: David King, Wymondham, Norfolk

Most computers today use the Network Time Protocol (NTP) to set their clocks. NTP is a special set of rules for communicating between computers over the internet, designed to synchronise clocks to the Coordinated Universal Time (UTC).

It takes time for messages to travel over the internet, so NTP takes this delay into account when computers are communicating the time with one another. In operation since 1985, NTP is one of the longest running, continuously operating, internet protocols.

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Dr Peter Bentley is a computer scientist and author who is based at University College London. He is the author of books including 10 Short Lessons in Artificial Intelligence and Robotics and Digital Biology: How nature is transforming our technology and our lives.