22 frets

Violas do not have frets. Nor do violins or cellos. Frets are found on stringed instruments such as guitars.

yes probably because i have a 20 fret and 24 fret bass and the frets on my 24 fret are much closer.also, on my 24 fret is says on the package:medium frets. and on the 20 fret has bigger frets so i presume that the 20 fret has "large frets"

Frets on Fire happened in 2006.

Not all guitars have frets, however, it is probably best to learn using frets.