Stephenson's Rocket was an early steam locomotive of 0-2-2 wheel arrangement. An 0-2-2, in the Whyte notation for the classification of steam locomotives by wheel arrangement, is one that has two coupled driving wheels followed by two trailing wheels, with no leading wheels. It was built for, and won, the Rainhill Trials held by the Liverpool & Manchester Railway in 1829 to choose the best design to power the railway.

Rocket was designed by Robert Stephenson in 1829, and built at the Forth Street Works of his company in Newcastle upon Tyne.

Though the Rocket was not the first steam locomotive, it was the first to bring together several innovations to produce the most advanced locomotive of its day. It is the most famous example of an evolving design of locomotives by Stephenson that became the template for most steam engines in the following 150 years.

The locomotive was preserved and is now on display in the Science Museum in London.

More Info: en.wikipedia.org