Is it necessary to clean the tongue and how to do that?

Cleaning the tongue can help improve taste perception and contribute to the overall cleanliness of a baby’s month. It can also help reduce bad breath and minimize the chances of infections. Most of my friends simply use a gauze (wrapped around the finger), moisten in warm water, and gently rub over the surface of the tongue. (One of my friend is using Nuk Oral Wipes. Available at guardian, $17.20: http://www.guardian.com.sg/oral-wipes-25s/p/129566) To facilitate the process, you can try cradling your baby with one arm and clean his/her mouth with the other.

For me, yes it is since baby is too young to rise his own mouth after feeding/meal. Just as Hui Qun has mentioned, it's for hygiene purposes and to remove any sort of milk build up that might have accumulate on his tongue. I use Nuk Oral Wipes too, but I bought them in bulk during baby fairs. It's approx. $99 per carton and it lasted for a pretty long time since I only use these when I am outside with my son. Otherwise at home, just a gauze will do as Hui Qun had explained.