The AGILE satellite is a space mission of the scientific program of the Italian Space Agency (ASI) focused on high-energy astrophysics, developed with the programmatic and technical support of the National Institute for Astrophysics (INAF) and the National Institute for Nuclear Physics (INFN). The AGILE satellite was launched on April 23, 2007, from the Indian base in Sriharikota in a quasi-equatorial low Earth orbit. AGILE is a very innovative space mission capable of reaching an optimal scientific performance for the study of astrophysical sources with detectors operating in the energy ranges 18–60 keV, 300 keV–100 MeV, and 30 MeV–30 GeV. The main scientific achievements of AGILE are related to the study of the most energetic Galactic and extragalactic cosmic sources, such as accreting compact objects (neutron stars and black holes), pulsars, supernova remnants (SNRs), and active galactic nuclei (AGN). AGILE made several important discoveries, including a novel mechanism of particle acceleration operating in the Crab Nebula, the emission of transient γ rays correlated with relativistic jet ejections from Galactic compact sources, the first evidence of hadronic cosmic ray production from an SNR, and the emission of very powerful γ-ray flares from accreting supermassive black holes in AGN. AGILE is now providing unique contributions to the study of gravitational wave source counterparts and cosmic neutrino emitters. Also, terrestrial applications are relevant for the science program: AGILE discovered γ-ray emission above 20 MeV from terrestrial γ-ray flashes produced by powerful lightning and thunderstorms.
