I see that some people use the social networks to communicate with their family members although they live in the same home. They communicate with their friends on social media although they see them every day. Why?

I don't know why. It makes no sense to me at all.

The kid that lives next door was sitting with his friends around a campfire in their backyard. There was complete silence, except for an occasional chuckle. They were all on their phones texting. When asked who they were texting, they all said "him" and pointed to someone in the group. They were sitting right next to each other but were texting each other.

I'm one of the person you talked about. The good thing about texting, if you wanna say something but you dont know the correct facial expression to come along with, you just have to type it. And for instance, I met my friend from 2pm till 4pm, we talked about stuffs. By the night we will talk again on the phone or texting coz we still got a lot of things to talk about. On the other hand, I'm a multitasker, i can talk about business plan while in the loo, i can do sexting at work too. Please dont hate me lol

I do it sometimes and I have no idea why xD It's nice if you don't want people to eavesdrop though, or if you don't want to be disruptive. Also I guess it's easier to explain some concepts through images or video than words

Mostly mental laziness, which both advances and results from the ongoing degeneration of societal mores relative to personal interaction and acceptable social behaviors.

While the capabilities of our smart devices are nothing short of miraculous, the trance-like fixation they can induce has often hijacked better judgment and attention to the point people will unwittingly compromise their identity, their dignity, even their own safety, and that of others. 

IMO, the potential perils of this mass preoccupation with smart devices and social media should not be ignored.