Like many great discoveries, Tarmac--a process for paving roads--came about quite by accident.

Near the end of the 18th century, a man by the name of John MacAdam first invented the method of "macadamizing" pavement by adding a layer of crushed gravel to surface a road. However, over time the gravel tended to grind and disintegrate. While it was fine for carriages and horses, newly invented motor cars would turn up huge dust clouds and send rocks flying from beneath their wheels.

Then, as luck would have it, British businessman E. Purnell Hooley was passing a tarworks factory in 1901, when he reportedly noticed a barrel of tar had spilled over the macadamized roadway. Someone had dumped gravel on the tar to cover it, and in traveling over this section of road, Hooley observed there was far less dust.

Based on this discovery, Hooley set out to make his own pavement mixture and launched a company to sell it. The company was Tar Macadam, and after changing hands in 1905, "Tarmac" became a huge success.

Tarmac is a registered trademark, yet has become a widely used term to describe any kind of paved road. Many people use the term to refer to an airplane runway, due to the fact that Tarmac was used extensively to construct runways during World War II. To this day, any large paved area at an airport is commonly referred to as a tarmac, whether it was paved with Tarmac or not.

Americans use the term "blacktop" to refer to tarmac, due to its color; though they use the term "tarmac" sparingly, and usually in reference to an airport runway. Brits, however, still commonly use the term to refer to any paved road or surface.

Today, tarless asphalt mixtures have largely replaced Tarmac, though many roads, airport aprons, and runways are still referred to as "tarmacs."