Literally means
'Peace be upon you' in
arabic
It is the prescribed
Islamic
greeting used by
muslims and is responded to by saying
Walaikum Asalam which means
Peace be upon you too
This form of greeting is said to carry a
reward of 10
blessings.
The
Salam can often be extended thus -
Salamun Alaikum Warahmatullahi Wabarakatuhu
which means
'Peace be upon you and the mercy and blessings of Allah'
(The extended greeting is said to carry a reward of 30 blessings)
It is stated in the
Quran that when the people of
heaven shall be asked by
Allah (The almighty) to enter it, they will be welcomed therein with this greeting of Peace.