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A Hayashi track is a track or path on a H-R diagram (HRD) that shows the evolution of a pre-main-sequence star, i.e., each point on the track indicates the position of that body at some point in its life. It outlines a particular phase in which the star is fully convective, the phase occurring in the early lifetimes of stars of up to 3 solar masses. The exact track depends upon the mass, metallicity and helium abundance (mass fractions) of the star. Such tracks are worked out numerically and checked against observations of star-forming regions. (Chushiro Hayashi first calculated a list of such tracks for a representative selection of stellar masses.) Stars which do not remain fully convective (i.e., larger than red dwarfs) subsequently follow the Henyey track.