Today you can buy this handy small item item for less than $1, but when Hungarian Laszlo Biro invented it in 1938, it was a revolutionary advance in the field of communication. What is it?

Hungarian journalist László Bíró grew tired of his fountain pen constantly smudging and leaking. He noticed that the ink used for printing newspapers dried almost instantly, leaving the paper smudge-free. Working with his brother György, a chemist, he developed a new type of viscous, quick-drying ink and a revolutionary new writing instrument to deliver it. Patented in 1938, their device used a tiny, free-rotating metal ball in a socket that would roll the thick ink from a cartridge onto paper.

This new pen was a massive leap forward. Because it didn't rely on a delicate nib or gravity-fed ink, it was far more durable and reliable than its predecessors. It could write on various surfaces and, most importantly, it didn't leak at high altitudes. This unique quality made it invaluable to Allied air force pilots during World War II, who needed a reliable writing tool for navigation in unpressurized cabins.

When first introduced to the public after the war, this invention was a luxury item, with early models in the U.S. selling for more than $10 each—the equivalent of over $150 today. It took years of manufacturing refinements, most famously by Marcel Bich, whose company Bic would go on to sell billions of them, to turn the once-revolutionary technology into the simple, disposable, and incredibly cheap everyday item we use today.