I haven't seen anybody mentioning it or even noticing it, like it's just the water we swim in now, but this month marks the fiftieth anniversary of the release of what would become a seminal, and is arguably the single most important, piece of social software ever created.

Written by Douglas McIlroy and James Hunt and released with the 5th Edition of Unix this month in 1974: diff.

https://minnie.tuhs.org/cgi-bin/utree.pl?file=V5/usr/source/s1/diff1.c

My friend @gvwilson has argued, and I am absolutely ready to believe, that you can divide the entire computational universe into "has diff and patch or doesn't", and that people living without it don't even have the language to recognize how bad they've got it, how many opportunities to share and collaborate have been silently denied them.

Word processors, spreadsheets, slides? "Track changes" is _trash_ by comparison. No programmer would consent to live the way we make office workers live.

@mhoye @gvwilson Not just computational. Any kind of document management. Instead of the diff format, people like solicitors and politicians deal with crap like 'In the 4th paragraph, before the word "cake", insert the word "delicious"'.