The search for planetary systems orbiting other stars or proto-planetary and debris disk observations of young stars have demonstrated that planets are extremely common objects as a consequence of stellar formation. While the quest to find bodies similar to the Earth is still on-going, the first spectra of exoplanets have been taken, signalling the shift from an era of discovery to one of physical and chemical characterization and the prospect to remotely detect life activities. With advanced high-resolution imaging observing techniques and ALMA we are probing the early phases of planetary system formation and evolution, slowly bridging the gap between stellar formation processes and the architecture of detected exoplanet systems. In the next decade space missions dedicated to transiting exoplanets (CHEOPS, TESS and PLATO) are likely to revolutionise our understanding of planet structure in addition the awaited James Webb Space Telescope will probe the atmosphere of a sample of small transiting planets.
The breadth of the techniques and approaches used in exoplanet research is intrinsic to the complexity of the topic. Exoplanet research focuses on a series of key questions ranging from the formation mechanics, structures and dynamics of the systems to the daunting question of the remote detection of life on another planet.