Character Creation - Blender Foundations: The Essential Guide to Learning Blender 2.6 - page 162

The strands we've been playing with are just guides for the real hair, which is about to materialize. Set
the head back to Object mode. Find the Children panel in the particle properties and change it from
None to Faces . A bunch of new controls show up. The ones under the Effects heading all deal with the
different ways that child hairs can clump around the parent strands, roughen themselves, and even kink
and curl. For now, all you need to do is set the Display value to around 5 and Render to around 25 .
This means that for each guide hair you styled, Blender will generate 5 additional hairs in the display, and
25 additional hairs at render time. The extras, called “child” particles, decide how to style themselves based
on the original guide hairs that you already worked with. A quick bit of math shows you that Blender
will render over 12,000 hairs at these settings (500 originals × 25 child hairs per guide). This is quite a
few, but it can easily go higher.
Figure 6.39 shows the head with these child strands enabled. Note that this is only one-fifth of the amount
that we'll render. We're not going to bother rendering the hair right now, as strand appearance is highly
dependent on materials, which we'll tackle in Chapter 7.
Figure 6.39 The head with child strands enabled.