How it started
On the 4chan forum people first teased each other with links to a picture of a duck on wheels. In 2007 someone slipped in Rick Astley's video instead of the expected trailer for the game GTA IV. The joke spread across the whole internet.
Rick takes it with humour
Rick Astley embraces the meme. In 2008 he made a surprise appearance at the Thanksgiving Day parade in New York, and his career came back to life. The music video has passed a billion views on YouTube.
Security
A Rickroll is harmless, but it teaches an important lesson: a link does not have to lead where it claims to. Before clicking, check the real address; the same goes for scam emails.