Maintenance for the week of October 5:
• [COMPLETE] ESO Store and Account System for maintenance – October 8, 8:00AM EDT (12:00 UTC) – 12:00PM EDT (16:00 UTC)
Doesn't matter where they purchased the game, everyone plays on either N.A. or EU server. All PC/Mac play together.
PS4 will have their own separate servers, as will Xbone.