The Gas Giants Jupiter and Saturn are the largest planets in the Solar System. Internally they are deep, heavy Hydrogen/Helium atmospheres on top of dense rock/ice cores without solid surfaces. What we see in our telescopes are just the tops of the clouds. This lecture describes the basic properties of the planets: their composition, atmospheres, weather, and internal structures. Recorded 2007 Nov 14 in 1000 McPherson Lab on the Columbus campus of The Ohio State University.