for M80. The diagram on the right focuses on the turn-off of
the main sequence and the red giant branch.
The diagram on the left indicates a number of different
objects. HB indicates the horizontal branch,
RGB is the red giant branch, SGB is the subgiant branch,
and BSS indicate the blue stragglers. Blue
stragglers will be discussed later in this review and the
interested reader can
consult  for a
discription of the other objects. Figure taken from Ferraro
et al. .