  We summarize the relationship between the free-free emission foreground and
Galactic H-alpha emission. H-alpha observations covering nearly the entire
celestial sphere are described. These data provide a template to isolate and/or
remove the effect of Galactic free-free emission from observations of the
cosmic microwave background. Spectroscopy and imaging provide two complementary
methods for measuring the H-alpha emission. Spectroscopy is favored for its
velocity resolution and imaging is favored for its angular resolution. With
templates of the three dominant foregrounds, namely synchrotron, thermal dust,
and free-free emissions, it may be possible to quantify the location and the
brightness of another foreground such as that from rotating dust grains.
