The M31 Globular Clusters in the Infrared

We review the infrared observations, both photometric and spectroscopic, of the globular clusters of M31. As a preliminary step, we summarize the observations in the infrared of individual stars in galactic globular clusters, then the observations of the integrated light of galactic globular clusters as well as the models that are used to interpret their properties. Another area that is discussed is the infrared observations of clusters in the Magellanic Clouds, their interpretation, and how they differ from galactic globular clusters. We also compare the observations of all these with the trends shown by normal elliptical galaxies.