In 2013, the IceCube Neutrino Observatory discovered a flux of high-energy neutrinos of extra-terrestrial origin, pushing the field of neutrino-astronomy into a new era. With energies exceeding 1 PeV, it is a good assumption that these neutrinos are associated with the unknown accelerators of high-energy cosmic rays. However, even 8 years later, the exact origin of these neutrinos remains a mystery. At this point, no strong correlation with any standard catalog of high-energy sources such as blazars, gamma-ray bursts, or similar has been found and the exciting 2017 detection of neutrino emission from the blazar TXS 0506+056 has only deepened this mystery. In this talk, I will describe the current state of our knowledge and give an overview of IceCube’s extensive and promising multi-messenger program trying to solve this mystery. In addition, I will show our plans for future extensions of the IceCube detector to higher and lower energies and how these will allow us to study the sources of astrophysical neutrinos even better.