reason

A build's reason is the way in which the build was triggered.

There are several methods by which Bamboo can 'trigger' (i.e. begin executing) a plan's build:

Build Strategy

Code updated — ensures that a plan build only occurs when something changes in the plan's source repository (which may affect the outcome of a plan build) .i.e. whenever one or more authors check in code.
Scheduled build — can allow a team to structure the day according to a predictable schedule. Scheduled builds are run regardless of whether or not any code changes have occurred i.e. at scheduled times or specified time intervals.
Manual build — allows you to ensure that builds are only triggered manually (or by the successful builds of other plans on which this plan is dependent).
Initial clean build — i.e. immediately after a new plan has been created.

Build Dependency

Dependency — a build can be triggered whenever another plan's build is successfully completed.

The trigger method for a plan's build is listed in the 'Reason' column on the dashboard.

Note that these trigger methods can only be configured by a Bamboo administrator. For more information please see Triggering builds.