The main focus of my research is the interaction of intense and short-pulsed radiation with matter. We study how atoms, molecules, clusters or nano-scale particles behave when irradiated with intense infrared, optical, XUV or X-ray light, and use different ultrafast light sources to image in real time photo-induced phenomena proceeding on femtosecond or even attosecond time scales. My research program combines lab-based studies employing intense few-cycle optical lasers and their high-order harmonics in the XUV domain with the experiments at the external Free-Electron Laser facilities such as the Linac Coherent Light Source (LCLS) at Stanford, FLASH in Hamburg, Germany and SACLA in Japan. In all cases we employ a variety of novel few-particle imaging techniques sometimes dubbed as "Reaction Microscopes" (based on Cold-Target Recoil Ion and Electron Momentum Spectroscopy, Velocity Map Imaging etc.), which allow us to measure emission energies and angles of several reaction products in coincidence and, thus, to obtain instantaneous snapshots of the electronic structure or nuclear geometry of the system we study. Creating a sequence of such snapshots in pump-probe experiments, we often aim at producing a "molecular movie" of ultrafast light-induced reactions. Examples of the processes we study include sequential and non-sequential multi-electron ionization of atoms, ro-vibrational wave packet motion and isomerization dynamics in simple molecules, interatomic Coulombic decay and non-local Auger processes upon inner-shell photoabsorption etc.