Muslims always greet people with these words; do you ever think, what does it means? and they say only instead of greeting with other words and message like people from other faith greet each other. e.g.
Hello, Hi, Hey, Namaste, Bonjour, yeoboseyo, مرحبا, হ্যালো, שלום, Zdravstvuyte, Hola, Kon'nichiwa, Nǐ hǎo, Hallo, Merhaba, Zdravstvuyte, Salom and many other words of greeting used in this world.
Lets understand the concept behind saying the As-salam-o-alaykum
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السلام عليكم | As-salam-o-alaykum
Meaning: May peace be upon you!
We can see the meaning; the person who is greeting is not only greeting you but s/he is actually making Du'a for you and s/he wants peace upon you from God.
Muslims in their prayer either it is their daily prayers (which is five times in a day), our prayers performed on occasion of Eids and other festivals, Muslims always conclude prayer by saying: As-salmualaykumwarahmatullah — (Means: May peace and blessings of God be upon you!). When they utter these blessings, they turn their heads to the right and the left side and put their gaze on their shoulder respectively. In doing so, they convey the message of peace to all mankind throughout the world.
Here in these videos you could see how a person uttering As-salmualaykumwarahmatullah and concluding his prayer.