As Salaamu Alaikum means ‘peace be upon you’.
It means that I guarantee I won’t harm you because I’ve wished peace on you. This is why it is hypocritical to wish peace upon someone, and then when not in his presence,
you stab him in the back (i.e. steal, backbite, slander, etc.).
Mufti Ismail Menk
When we talk about someone, it’s easy to fall into one of these sins:
1. Gheebah / backbiting – to say what is true about a person in a manner that he/she dislikes
2. Buhtaan / slandering – to say what is untrue about a person
3. Ifk / rumors, hearsay – to spread what was conveyed to you (without verifying if it’s true or not)
4. Nameemah / gossiping – to stir enmity between friends
1 & 2. Backbiting & Slandering:
Rasulallah sallallahu ‘alaihi wasallam said: “Backbiting is talking about your (Muslim) brother in a manner which he dislikes.” It was said to him: “What if my (Muslim) brother is as I say?” He sallallahu ‘alaihi wasallam said, “If he’s actually as you say, then that’s backbiting; but if that isn’t in him, that’s slandering.” 
3. Spreading Rumors / Hearsay:
“It is sufficient that a man has lied who narrates everything that he hears.” 
“A gossip monger will never enter paradise.” 
On the social media platform, it’s super easy to hit the “share” button without thinking of the consequences of our actions. So have second thoughts before we share something – Will I commit any of these sins by sharing this post/photo/video? This also of course applies in our everyday interaction outside the virtual world.
 Bukhari & Muslim