IceCube real-time alert system

In 2013 the IceCube collaboration reported the first detection of a diffuse flux of astrophysical neutrinos. However their sources remain unknown. The fact that no distinct sources have been identified could be because there is a large population of weak sources, either steady or transient. The IceCube real-time program is motivated by the second possibility. Taking advantage of its continuous full-sky sensitivity, IceCube has established several alert channels in order to trigger observations from more sensitive instruments with smaller fields of view. A coincident observation of an enhanced electromagnetic flux or gravitational wave could provide strong evidence for a potential neutrino source. In this proceedings we discuss the technical aspects and science goals of the IceCube real-time alert program, concentrating on the channels most interesting for the gamma-ray community: the Gamma-ray Follow Up, Extremely High Energy and High Energy Starting Events. For completeness we also discuss the X-ray/Optical Follow-up channel.