Tarmacadam is a concrete road surfacing material made by combining tar and macadam (crushed stone and sand), patented by Welsh inventor Edgar Purnell Hooley in 1902.
It is a more durable and dust-free enhancement of simple compacted stone macadam surfaces invented by Scottish engineer John Loudon McAdam in the early 19th century.
The terms "tarmacadam" and tarmac are also used for a variety of other materials, including tar-grouted macadam, bituminous surface treatments and modern asphalt concrete.
Ironically, although John Loudon McAdam himself had been a supplier of coke for Britain's first Coal-Tar factory, he never in his own lifetime advocated for the use of tar as a binding agent for his road designs, preferring free-draining materials (see the page Macadam).
In 1901, Edgar Purnell Hooley was walking in Denby, Derbyshire, when he noticed a smooth stretch of road close to an ironworks.