The term evolutionary track is used for the track across a H-R diagram plotting a star's changes over its lifetime. (The term stellar evolution indicates such changes of a single star, or a single type of star, rather than the "biological" sense of evolution regarding how successive generations differ.) An evolutionary track can be plotted as a curved line from a point plotted for the star at some point in its life (presumably early in its life, such as when it enters its main-sequence phase), leading to a later point in its life (e.g., its core collapse supernova). It might at some point enter the H-R diagram's red-giant region and possibly its asymptotic giant branch region. Hayashi tracks are a set of such tracks calculated for the pre-main-sequence star phase.