Prior to the introduction of file notifications in MOVEit Central 3.1, in order for a task to notice a file, the task had to be scheduled to run repeatedly. Each time the task was run, it checked for files that matched a given mask. If no such files had arrived, no action was taken, and the task would be run again later by the scheduler. In order for a task to see a file shortly after its arrival, the task had to be scheduled to run often, causing extra overhead for both the remote server and MOVEit Automation itself.
File notifications allow you to run a task only when files that are associated with the task are actually available. The task runs almost immediately after the arrival of a file. The MOVEit Automation component that implements file notifications is called the notifier.