This is an entry in our Disneyland 101 Glossary: Disneyland Resort definitions in under 101 words, from Mouse Brief.
Disneyland Resort’s virtual queue service makes use of boarding groups. If you successfully join a virtual queue for an attraction, you will be assigned to a boarding group. Throughout the day, boarding groups are called in numerical order. The Disneyland app will notify you when your boarding group is called and it is time to come experience the attraction. You boarding time is valid for a one hour window. For more on how to use virtual queues, please visit our guide here. Virtual queues are a free-with-admission service, for the paid Lightning Lane services, please read our guide here.