CERN is a huge science lab on the French–Swiss border, near Geneva. People there study the tiniest pieces that make up everything — smaller than atoms. The famous machine is a giant ring under the ground that sends those pieces round very fast so they smash into each other; from the smash, scientists learn how the universe is put together. The name is a French short form, and it still has “nuclear” in the old wording, though actually the work today is particle physics, not building bombs or power stations. It started as a club of European countries; more countries have joined over time. You will also hear that the World Wide Web was first built there so scientists could share papers — that part is true, which is why the letters CERN turn up in tech history as well as in physics news.