Why does the popular LINE?

Do you know "LINE"?
It is one of SNS services.You can chat and phone for free on the LINE.
60 million people in the world use this, and 28 people in japan use this.

The mainstream of SNS is Facebook and Twitter,but LINE was spread early among young people.
...Then why?

I think there are 3 reason.
First,specialized in smart phone.
Recently, a lot of people use smart phone.So LINE is very useful for these people.
I using smart phone too,I often use this.

Second,you can communicate in the "closed network".
Facebook and Twitter are  very "open place".
It is also good point and,it is also bad point.
On the LINE,You can communicate with friend feel free in the "closed network".
Group chat is a very useful for me.

Third,you can send "stamp".



As shown in the picture,there are many kind of stamp.
It can tell the feeling without any words.
There is a stamp shop,and you can buy stamps on the internet.

These services are very useful, but we shouldn't forgot "face to face".
It is best communication for us.
If we communicate only with SNS,may be we forgot compassion I think.
So it is not good to rely too.We should use these service very carefully.