Which came first, the internet (ARPANET) or Windows?

the internet (ARPANET) came first, by 16 years. The first message was sent between two networked computers.

Side by side

the internet (ARPANET)

On 29 October 1969 a team at UCLA tried to send the word "login" to Stanford. The system crashed after two characters, so the first message ever sent over the internet's ancestor was "lo". By the end of that year the network had four nodes. The internet is twenty years older than the Web, and confusing the two is the single most common error in this whole subject.

Windows

Windows 1.0 shipped in November 1985, twenty-two months after the Macintosh, and it was not an operating system — it was a graphical shell running on top of MS-DOS, and remained so until Windows NT in 1993 and the consumer transition with Windows XP in 2001. Version 1.0 could not even overlap windows: they tiled, because Apple's legal position on overlapping windows was unresolved.