Visit Aurora, the Live Transport Tracker in Melbourne
Children aged 4 are allowed to travel free throughout the network, and don't need to have a myki.
Children aged 6 years old to 16 years old may have a 'Children' concession fare. They do not need to carry any proof of age around with them. 16 year olds may use Mobile Myki if they have an Android Phone.
Teenagers aged 17 and 18 must carry officially issued proof of age ID (such as a passport, learner permit, or Proof of Age card), or another concession entitlement (such as a PTV School Student ID or Health Care Card). This is so people do not fake their age to receive concession entitlements. 17 and 18 year olds may use Mobile Myki if they have Android Phones.