You decide who is allowed where and when
Your wristband does not only serve as your wallet, but also as your ticket to enter the event. As the organiser you decide for which (part of) events a visitor is authorized. Visitors themselves have access to this information, since the events they are authorized for can be displayed in email communication, the web application or a specific event application.
It is possible to check live who already entered the event and who is yet to arrive, and to send messages, push notifications, and more to only those visitors who are attending the event on that very moment. It is even possible to automatically send a message instantly when a visitor checked in at the event.