In 1930, László Bíró, a Hungarian-Argentine inventor observed children playing with marbles in a puddle, noticing that the marbles left a trail of water in their wake. Inspired by this observation, he conceived of a mechanism for a pen that used a ball-shaped metal nib to place ink onto a page.
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A ballpoint pen is widely referred to as a "biro" in many countries, including the UK, Ireland, Australia and Italy. Although the word is a registered trademark, in some countries it has become genericised.