Multi-messenger astronomy has experienced an explosive development in the past few years. While not being a particularly young field, it has recently attracted a lot of attention by several major discoveries and unprecedented observation campaigns covering the entity of the electromagnetic spectrum as well as observations of cosmic rays, neutrinos, and gravitational waves.
The exploration of synergies is in full steam and requires close cooperation between different instruments. Here I give an overview over the subject of multi-messenger astronomy and its virtues compared to classical "single messenger'' observations, present the recent break throughs of the field, and discuss some of its organisational and technical challenges.