The Character State describes or designates the condition in which the character is found.
For example if feather color is the character, then red, yellow or black might be the state. If fur is the character, then present or absent might be the state (UCMP, 2011).
An Ancestral Character State (also called plesiomorphic) is the old state, or the condition of an identifying feature that is present just before a character changes its state.
The Derived State (also called apomorphic) is the new state or state present after a character has changed or evolved (Carlson, .1999).
Carlson, S. (1999). Evolution: investigating the evidence. Paleontological Society Special Publication, 9. Retrieved from http://www.ucmp.berkeley.edu/education/events/carlson2.html
University of California Museum of Paleontology (2011) UCMP Glossary: Phylogenetics. Retrieved from http://www.ucmp.berkeley.edu/glossary/glossary_1.html