[filmor]

You only need some official document (ID card, passport, whatever) that matches the name and birthday. If you are a tourist, you must have a passport or ID card close by anyhow.

[usr1106]

Right, that's a requirement at ticket inspections. At least in theory, in practice in 99% it's not going to be checked.

For buying it, ID might be required at some sellers, but typically it's not.