Particle systems within Maya are composed of a particle shape to hold the particles and a number of emitters to generate new particles which get stored in the shape node. The hypergraph view above shows this relationship between the emitter and shape. You may also notice that the emitter and shape take an input from the global time node. This provides the nodes with notification of when the time changes so that new particles can be added if needed.

 

 

A simple perticle system with an emitter and particle shape only is not all that visually interesting. To make the motion of the particles better represent natural phenomena, dynamics fields are applied to the particle shape to apply forces to each individual particle.

The above hypergraph view simply demonstrates a particle system with a gravity field applied.