When a device controlled by NI-DAQmx does something, it performs an action. Two very common actions are producing a sample and starting a waveform acquisition. Every NI-DAQmx action needs a stimulus or cause. When the stimulus occurs, the action is performed. Causes for actions are called triggers. Triggers are named after the actions they cause:
In addition to specifying the action you want a trigger to cause, you must select the type of trigger to use, which determines how the trigger is produced.