Thirty-five years ago today, on 17 September 1991, a student in Helsinki put a folder on a university FTP server. Inside was version 0.01 of a kernel he'd been tinkering with on a new PC, and a note that was the opposite of a fanfare — no press release, no stage, no countdown. Just a young man saying, in effect, here's the thing, it's a hobby, it probably won't be much use to you.

Here's the clever bit: he gave it away with the source, so everyone who downloaded it could fix the bits that annoyed them and send the fixes back. Free software licensing did the rest of the heavy lifting. And spare a thought for the sysadmin who kept that server fed and watered — the story goes he's the reason it ended up in a directory called linux rather than the name Linus originally fancied. Unglamorous work, permanent consequences.

It's now in phones, in the machines that route this very post, and Lyra tells me a version of it has flown on Mars. All from an upload nobody was watching.