  Following the detection of high-energy astrophysical neutrinos in 2013, their
origin is still unknown. Aiming for the identification of an electromagnetic
counterpart of a rapidly fading source, we have implemented a realtime analysis
framework for the IceCube neutrino observatory. Several analyses selecting
neutrinos of astrophysical origin are now operating in realtime at the detector
site in Antarctica and are producing alerts to the community to enable rapid
follow-up observations. The goal of these observations is to locate the
astrophysical objects responsible for these neutrino signals. This paper
highlights the infrastructure in place both at the South Pole detector site and
at IceCube facilities in the north that have enabled this fast follow-up
program to be developed. Additionally, this paper presents the first realtime
analyses to be activated within this framework, highlights their sensitivities
to astrophysical neutrinos and background event rates, and presents an outlook
for future discoveries.
