Nice post over at Medium.
After reading it I went asking my 18-year-old sister if she knows this services and how she uses them.
My takeaway from a typical middle european girl is that she mostly uses Facebook, Whatsapp and Skype. For finding interesting stuff she mostly uses pinterest, but doesn’t pin.

Instagram is for "pepping up" photos. She doesn’t understand why anyone would use Snapchat and noone in her circle of friends uses tumblr.

What do you say? Is Snapchat an "american thing" and what’s up with "Whatsapp"?

Whatsapp makes sense to me. Most of my sister's friends have iPhones, so they can SMS w/ iMessage for free. But Whatsapp is great across devices and carriers.

Surprising to hear about Skype and Pinterest though. Is Skype for instant messaging or video chatting?

They use Skype mostly for chatting and sometimes calling with or without video :)

WhatsApp is really popular in Western Europe because of its group functionallity. Many teenagers are in whatsapp-groups with their friends, or even different groups of friends. Resulting in one very relevant social network. Because the users know who else can read their messages they know what can be said. The most trusted environment..

I find myself in groups with friends who don't even use Facebook or twitter anymore, because the ones who really matter to them are in their whatsapp groups.

For startups this should be a great insight and inspiration. Whatsapp is like path, but for more groups, private streams of stories.