Many people seem to think that roller skates are a relatively recent invention, and a popular 20th-century kids' toy. However, roller skates have actually been around for over two centuries, and have many other uses apart from child's play.
The most commonly seen kind of roller skates today are actually roller blades, also known as inline skates. They have all the wheels in a line instead of arranged in the classic car-style formation, which allows you to travel much faster at the expense of making it a little more difficult to balance, a similar trade-off to that made with a two-wheeled bicycle.
In fact, the original purpose of roller skates was as a means of transportation: a kind of 'wheeled shoe' that you could fix to your feet and move from one place to another with little effort. Although it is rare, some people still use them this way today ' particularly teenagers, but also office workers in cities who don't have too far to go and don't want to take a bike.
Roller-skating is also a popular sport, and it is even thought that it might soon be added to the Olympics. Skate-parks that have been designed to accommodate the resurgence of skateboarding can also be easily used for roller-skating, and skaters can pull off similar tricks and manoeuvres to skateboarders this way. Roller skate racing is also quite popular, with people competing to get from one side of an obstacle course to the other in the fastest time.
If you're still not convinced of the popularity of roller skating, it's worth noting that every week in many of the world's largest cities, tens of thousands gather and skate together. The biggest and most famous event is Paris' Friday-night Pari Roller, but smaller events can be found in Berlin, Tokyo and London, among others.