The build queue in TeamCity, by default, ensures that builds are run in the order in which they came in (the classic First In First Out way).
Tip
Build configurations in the queue can also be rearranged or even removed from the queue manually from the Build Queue page.
While this works for most cases, there are situations when we might need to ensure that certain build configurations are triggered as soon as possible. For example, build configurations that deploy to production definitely need to have agents assigned to them as soon as one becomes free.
At the other end of the spectrum, we can also have build configurations that may have low priority, and can be run only when other build configurations are not looking for agents. Build configurations running regression tests are examples of those that can have low priority. These tests can run for a long time, and it doesn't make sense to hold up other builds.
TeamCity has the ability to define the priorities of build...