Trigger conditions are used to determine whether a trigger should start the build as soon as the project is triggered or whether it should then have to pass a set of "conditions" before starting.
Condition Name
The name you wish to call this condition.
Description
The description you want to give this condition. Can be used to make it clear why you have this condition set.
Condition Type
The type of condition to add to the project. Once you have added the condition, you cannot change this value.
Active
Determines whether this condition is currently active.
Applied To
A trigger condition can be applied to all triggers, meaning that when any trigger tries to start a build this condition will be evaluated. They can be applied to all triggers and users, which means that whenever a build is started this condition will be evaluated (with the exception of a user by-passing the build queue when starting the build). You can also choose to only evaluate this condition when the build was started by a specific trigger.
If Condition not met
This is the action the build server will take when a build is triggered and at least one of the conditions was not met. Discarding the build will cause the build server to forget that the build was ever triggered, where as setting the server to try again will cause the build to be started at a later time. When the build is set to start at a later time, the trigger conditions are re-evaluated before the build is started.