I believe I got my original GitHub invite from another HN user, back in the days when it was still invite-only. I confess at the time I didn't really "get it",

I believe I got my original GitHub invite from another HN user, back in the days when it was still invite-only. I confess at the time I didn't really "get it", despite having played with Darcs and the like prior to this. But (in retrospect), I don't think it's really that complicated. SourceForge, back in the day, had a really atrocious UI. As a highschooler navigating CVS and SVN repos for the first time, it was really difficult to figure out how to even download source code (this was especially horrific with CVS on Windows), let alone contribute in any meaningful way. Discussion on these sites required you to sign up for a mailing list. I think Gmail was just barely a thing, but prior to that as a student I would have been stuck with some awful Hotmail account or similar. Anyway, the hurdles were high and therefore this selected for "serious" contributions (or people willing to put up with a lot of obstacles). SourceForge may have supported some sort of bug tracker, but I don't remember ever interacting with a project that used it, so in practice people were splitting their various components (code, mailing lists, bug tracker) between several different sites. Ignore Git for a minute. GitHub, if nothing else, had a really slick UI. That UI put code front and center, so it was (finally!) obvious what sort of project you were actually looking at. I think it can't be underestimated how much this uniformity makes code easier to browse, as compared to the vast gulf in difference in quality between the best and worse homepages of open source projects prior to this. For fun, here's one that I authored back in the day. The home page here is actually kind of informative, but you can see how if this is all you get, the results are going to be all over the place: https://ip-interfaces.common-lisp.dev/ https://ip-interfaces.common-lisp.dev/ Beyond this, GitHub offered a permissionless collaboration. In the bad old days of open source, I could clone a repository, and I could write patches, but the cost of setting up forks was prohibitive. This is one of the things I didn't "get" at the time, but GitHub made it practically (and socially) acceptable to just fork whatever you needed, change something, and submit it. Or not, it didn't matter. Whether you intended for your experiments to be useful to anyone else or not, it dramatically lowered the cost of starting and maintaining those experiments. And that I think dramatically changed the face of open source software (for the better).