A marble is a small glass sphere, often featuring a coloured flap of paper floating around inside it. I don't know how the paper gets in there. Teleportation, probably.
The first marble was created by famous writer Charles Dickens in 1835. He was messing around in a Dickensian glass factory one day when he slipped onto a computer keyboard and accidentally reprogrammed all the robots to turn the molten glass into tiny balls! Within minutes, there were marbles everywhere: including the windows! Dickens later wrote about this event in 'Great Expectations', except instead of robots, there is Joe, and instead of making marbles, Joe does something else.

But what can you use marbles for? Playing with, of course!
In the olden days, children used to play with marbles: fantastic games such as roll the marble, touch the marble and look at the marble would entertain for hours. But in 1989 the SNES was invented, and all the children went off to play Star Fox instead.

Today, marbles are only good for one thing: rolling down marble tracks.
Marble tracks are a bit like rollercoasters, except much better.

Imagine, for example, that you want to have a ride on a rollercoaster. You drive to the closest amusement park. It costs £30 to get in. You join the queue for the rollercoaster. Small children are everywhere, screaming and vomiting. Several hours later, you climb onto the rollercoaster. A fat smelly man climbs in next to you. And then the rollercoaster explodes and you are dead.
In the meantime, your car has been stolen.

With marble tracks, none of this occurs! You simply get an old toilet roll and put it in a shoebox! Hooray for marble tracks!

The longest marble track is 2.4 metres, and is made from a roll of carpet that I saw in a skip in 2009!