[karmonhardan]

IIRC Material Design actually came before iOS' pivot to Immaterial Aero We Have At Home. Metro was indeed first, though, so kudos for actually mentioning it. Everyone seems to forget that the Zune was what really got things rolling.

[grishka]

Material came out in mid 2014. I know that for sure because I was at the Google I/O where they presented it together with Android L/5. iOS 7 was released in 2013.