The change from gas or vapour to liquid is called condensation. To observe condensation you may do this simple activity.
Take a glass and keep it inside the freezer for sometime. Take a saucer and upturn it on a glass of hot milk for a while.
Remove the glass from the freezer. You will find droplets on its outer surface. When you remove the saucer from the glass of milk you will find droplets on it too. This is due to the process of condensation.