[eonwe]

On chat applications: In Finland no one used AIM and everyone used messenger.

I suspect this was the norm also elsewhere in Europe. I am talking about Messenger 4.6 that came built in with windows xp and its later versions, not the business version.

[Ennea]

The most popular choice in Germany used to be ICQ, at least based on my own friend group and various conversations I've had over the years.

[Tijdreiziger]

In the Netherlands, MSN Messenger (commonly abbreviated just 'MSN') was essentially a monopoly, although at that time it was only used by young people (older people still just called each other on the phone).

With the rise of smartphones though, it ended up being supplanted by WhatsApp, with the ill-conceived migration to Skype killing off most of the last stragglers.