This is what the basic structure of a Particle effect looks like in the Node view. This structure can change depending on the type of effect you are trying to create.
Particle effects are colour coded to make them easy to identify by colour and function. Each colour represents a different function. For example, Action nodes, such as Velocity, Move-Particles and the Sprite Emitter are bright purple. These colours can be edited in the Preferences dialog box by going to Edit/File > Preferences > General tab > Edit Colours button > Particle tab.
In addition to defining groups by colour, node in-ports and out-ports are also colour-coded. In the network shown in the illustration above, the Particle-Baker is dark yellow and the Particle Visualizer purple. Look closely and you will notice that the in-port on the Particle Visualizer, where the Particle-Baker is connected, is also dark yellow. Similarly, the out-port on the Particle-Baker, where the Particle Visualizer is connected, is purple.
This system gives you an idea, at the very least, of what type of node is needed to fill a specific port.
|•||Visualizer - This node assembles a particle system through its middle port. It can accept a Peg on either side. The system is flattened at this node and generated as a single image. This lets you move the effect's position in your scene or change its render order.|
|•||Action - These nodes affect the particle dynamics; they determine how they are created and moved around in space. If there are multiple Action nodes hooked to a composite, they are executed from right to left. Due to this ordering, there should generally be an emitter on the right-most port.|
|•||System Composite - Unlike a regular composite that reads all the position information from its in-port nodes and combines them accordingly, a System Composite is specifically designed to handle Action node information.|
|•||Baker - These nodes allow you to make decisions about the particle system's position, angle, number, etc. the same way that a baker would make decisions about the ingredients that go in a cake.|
|•||Region Composite - This node combines Region nodes. In case you have more than one Region in your effect, this composite will help define the position and render order of the different Regions.|
|•||Region - These nodes are used to define the region from where the particles are emitted. These regions can be Planar or 3D.|