Your Shape

Your shape is actually a series of body part appearance settings.
Shapes can be found for purchase from shops specializing in
avatars or avatar customization, and for free from “freebie”
places in SL or as free sample offerings through those shops.
Sometimes a skin has a shape included to compliment the way
the skin is created, but including that doesn’t determine the
quality of the skin and makeup either way.

 You can alter your own shape in your Edit Appearance dialog
box, with a vast assortment of subtle changes to almost every
part of your avatar’s body.  Some avatars choose to use a
pre-made shape suitable to taste in appearance.  And a full perm
shape means you can adjust all settings and save it for yourself.