The emitter is the place where particles are born and given their initial velocity and direction. Here are all the controls for emitter shape/type and position, initial velocity and how many particles are emitted.
Particles/sec
Controls how many particles are born each second. High values means lots of particles and can be slow to render, low values means sparse particles and are normally fast to render. This value can be keyframed so that particle emission varies over time.
Emitter Type
Sets the shape and functionality of the emitter. More about Emitter Types
Position XY & Position Z
The position in 3D world-space where particles are born. Theese values can be keyframed over time to create trail effects and such.
Direction
Controls in what direction the particles move initially. More about Directions
Direction Spread
Controls the spread of the particle beam when used with: Directional and Bi-directional, Disc and Outwards direction types. Disabled for Uniform emitters. Disabled for Light emitters, read more about Light Emitters.
X,Y and Z Rotation
Rotates the emitter around X,Y and Z axis.
Velocity
The initial velocity of newborn particles.
Velocity Random
Adds randomness to the initial velocity of newborn particles. This means that the particles are born with varying initial velocity.
Velocity from Motion
Lets the particles inherit velocity from the emitter. For this parameter to have any effect, the emitter must be in motion. Negative values gives a feel of a "jet", the particles spray opposite to how the emitter moves and so they appear to be pushing the emitter forward, like a jet engine. Positive values gives the effect of something that is letting of particles as it moves, like stars from a magic wand. Positive values also gives a look of particles getting caught in the draught of the moving emitter. A value of zero means that the emitter motion has no effect on particles initial velocity. This parameter can easiest be tested and understood in the Preview when shift-clicking to emit particles interactively.
Emitter Size X,Y and Z
Sets the size of Box, Sphere, Grid and Light emitters. For Point emitters, this control is disabled. For Layer and Layer Grid emitters, only the Z parameter is enabled since their X and Y size is controlled by the size of the layer.