Family and friends

to be connected by social media, to call, to text someone (usually far away)
My friend moved to a different city, but we still keep in touch. He sends me birthday cards and I call him once a week.

To have same interests and hobbies
Me and my friend have nothing in common, he likes jazz, I like pop music. But it's interesting to hear him talk about it.

To ask information about the person, to know him/her better
Me and my girlfriend live together now, it's a good way to get to know each other better.

To have different level of education / life conditions 
I was raised by a middle-class family and my friend has always been very rich. We come from different backgrounds, but it doesn't matter to us.

People you don't know / haven't met before
I don't like when strangers talk to me, I feel nervous.

To be able to talk and discuss your feelings
It's important to get an emotional support from your friends.

To have a good relationship with someone / to "click" 
I can say I get on with kids very well. The key is to be positive and know how to entertain them.