Polymer clay is a versatile and exciting medium. It is a manmade plastic material that consists of PVC particles and pigments suspended in a plasticiser.
Polymer clay is fantastic as it doesn't air dry like other clays (unless it is manufactured as a specific 'air-dry clay',it must be baked), it bakes at a low temperature and so it allows for much more flexibility. You can achieve so many things with polymer clay that are not possible with other mediums.
Be warned though - polymer clay is very addictive!!