Abstract: It is a very important problem to determine the ages of stars in the stellar physics. Whether it can be well resolved or not is related to many other important issues in astronomy. The ages of stars are directly related to those from estimating ages of extrasolar planets to the age of the universe. In this paper, it is briefly described which ways in astronomy can be currently  used to infer and estimate the ages of stars and what difficulties there are still to be introduced by the uncertainties in the evaluation of stellar ages with these methods.

Key words: star, age of star, , evolution of star, extrasolar planet, age of universe