Which came first, Windows or YouTube?

Windows came first, by 20 years. Microsoft shipped Windows 1.0.

Side by side

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.

YouTube

The youtube.com domain was registered on Valentine's Day 2005, the first video — "Me at the zoo", 19 seconds of a co-founder at San Diego Zoo — was uploaded on 23 April, and the site opened publicly in the winter. Google bought it in November 2006 for $1.65 billion, about twenty months after the domain was registered. It is younger than Facebook by a year and older than Twitter by one.