[renhanxue]

StuffIt is a thing you might be nostalgic about if you used MacOS 7 through 9 or so in the 90's. I'm surprised it still exists, I don't recall using it on OS X at all.

[alsetmusic]

I think it was there for the first few years. I seem to remember a revised app icon when they went from 32x32 to 128x128. I don't think it mattered much, though.

[RandallBrown]

I remember many apps being distributed as .sit files on OSX at least in the old Tiger and Leopard days.

[gcanyon]

I came to post roughly this. I had literally forgotten StuffIt was a thing, until the headline brought it all flooding back.