Astronomy Colloquium

White Dwarf (WD) stars are the most common stellar remnant, being produced by all stars below about 8 times the mass of our sun. Put in a close binary, a WD can gain mass from a companion and undergo a variety of bright, dynamic outburst phenomenon driven by both accretion and thermonuclear explosion. I will discuss how we study the WDs in these systems, during both outburst and quiescence, and what we are learning about their population as a whole and how these binaries form and evolve. I will highlight the ignition of the brightest outbursts they make: Classical Novae -- due to thermonuclear runaway in hydrogen-rich material on the WD surface -- and Supernovae -- due to carbon-burning thermonuclear runaway in the deep interior. Particular attention will be paid to how the features of the evolution of the binary might determine aspects of the explosions. These systems are thought to produce the Supernovae of Type Ia, which have remarkably regular characteristics and are therefore of great interest as standard candles for cosmology. Interesting puzzles remain in our theoretical understanding of these systems and their remarkable outbursts.