The Queue allows players to start subsequent constructions, researches and upgrades.
The Building queue can contain up to 3 subsequent processes, 5 for Premium and 6 for Platinum users. The Queue is one and the same for all Zones. Buildings in one zone are being built one after another, while those in different zones are being built in parallel. This means that if you start building a Metal mine and a Metal storage, their constructions will run simultaneously because they are placed in different zones.
Similarly, the queue for researching sciences is up to 3 slots, 5 for Premium and 6 for Platinum users. Here, all sciences are researched one after the other, regardless of the type of the sciences being researched.
There also is a units construction Queue for ships and defence, its slots are not limited.
When a process in the Queue is canceled, the next one in the Queue takes its place. When a process, the finishing of which is a requirement for starting the next process in the Queue, is canceled, the next one will not start at all.