A sampler is an digital instrument that uses stored audio sounds, samples, usually from recorded sounds, and then plays them back at the desired pitches.  When you hear a digital organ being played it is actually playing back digital recordings of a real pipe organ.  Unlike analog organs of the past, digital organs have much in common in with each other today.  What differentiates today’s instruments isn’t the tone generation system, it’s the quality of the sample.  This sampler technology has been a revelation to music. 
In a virtual organ the digital sampler is the virtual pipes.  In a real pipe organ the different types pipes are arraigned in groups called ranks.  These ranks carry over to the digital sampler. In Miditzer a midi channel is dedicated to one rank of pipes. 
 

Software samplers have surpassed hardward samplers in features and power.  They are powerful because they can play many voices at one time.  Miditzer's powerful built in sampler offers nearly unlimited polyphony.  This polyphony of voices is important because the organ can play so many pipes at the same time.  Unlike a digital piano or synthesizer that will play one or two voices per note on the keyboard, an organ can play many more voices.  For example if you have selected 12 stops on the organ it will play twelve voices per note on the keyboard.  When a 4 note chord is played 48 voices will sound, and that’s with just one hand.  Add to that another hand and two feet and the amount of voices grows.  As with an orchestra, the sound on the organ is from multiple sources.