An availability zone is the city where your VPS runs. You choose it when you order. The closer the server is to your users, the faster it answers them.
Where you can deploy
London
New York
Paris
Amsterdam
Frankfurt
Bucharest
Helsinki
Warsaw
Madrid
Not every product is offered in every location. The order page shows the locations you can choose for each plan.
How to choose
Choose the location closest to most of your users. If the server is only for you, choose the one closest to you. For example:
Users in the UK and Ireland: London
Users in Western Europe: Paris, Amsterdam, Frankfurt or Madrid
Users in Central and Eastern Europe: Warsaw, Bucharest or Helsinki
Users in North America: New York
To use another location later, you can deploy a new server there, or ask for your current server to be moved, as shown in Migrating a VPS to another region.