Pulsar Timing Arrays

Pulsars, and especially millisecond pulsars, can be used as precision clocks to explore a wide range of phenomena. An array of millisecond pulsars distributed across the sky can be used to detect low-frequency gravitational waves by searching for a correlated signature between pulsars, arising from the influence of gravitational waves at the Earth. These pulsar timing arrays complement other methods of gravitational wave detection in their frequency coverage and the physics they probe. I will introduce the basics of pulsar timing and discuss how it applies to the detection and study of the gravitational wave Universe. Pulsar timing array collaborations, current results, and future prospects will also be presented.