Traits are features you breed for on a cat. For example a particular looking tail, ear, or eye.
I like to split traits into 2 categories: Starter Traits & Breedable Traits.
Starter Traits are anything you can buy at the KittyCats main store in their starter packs or collection cats. These starter traits can also pass to cats you breed so you will see them on cats also in the secondary market too. As they are the "default" traits, they are not considered to be very valuable as no work is needed to obtain these. However more than often these starter traits hide something better underneath them.
The current list of "default" starter traits are as follows:
Furs:
Genesis I & II
Domino, Coco, Flame, Smokey, Diamond
Eyes:
Curious Shape, Big Pupil
Genesis Earth, Genesis Odyssey, Genesis Medow, Genesis Water, Genesis Sunshine
Shade:
Natural
Ears:
Genesis
Tail:
Genesis
Whiskers:
Silver/Guitar
A Breedable trait is everything else. You can find a good list of these in Sagas Docs:
http://kittycats.biz/forum/showthread.php?tid=2351 These vary greatly in desirability and value.
Hope this helps explain what is a trait