Finally, we notice that globular cluster H-R diagrams have stars located along a horizontal branch running toward the blue side of the diagram. Studies of the evolution of low-mass stars show that those stars loop far to the left in the H-R diagram as they fuse helium in their interiors. The H-R diagrams of globular clusters trace out the evolutionary tracks followed by low-mass stars and once again confirm that our theories of stellar evolution are, in general at least, correct.