The ages of stars are based upon a comparison between observations and stellar evolution theory. I will provide an overview of the age determination process, including a discussion of possible sources of errors.
Stellar ages provide valuable insight into two key questions in astrophysics.
The former question requires a study of the relative ages of a large number of stars, while the latter question involves the study of the absolute ages of the oldest stars. I will review recent progress in stellar age determations as they relate to formation of the Milky Way and the age of the universe.