What are the generations of android OS ?

Cupcake:
Android 1.5

Donut:
Android 1.6

Eclair:
Android 2.0
Android 2.1

Froyo: ( short for "frozen yogurt" )
Android 2.2

Gingerbread:
Android 2.3

Honeycomb:
Android 3.0
Android 3.1
Android 3.2

Ice Cream Sandwich:
Android 4.0

Jelly Bean:
Android 4.1
Android 4.2
Android 4.3

KitKat:
Android 4.4