Recoil-ion and electron momentum spectroscopy is a rapidly advancing technique that measures the vector momenta of ions and electrons resulting from atomic or molecular fragmentation. Known as Reaction Microscopes, these instruments combine large solid angles (close to $4\pi$) with high momentum resolutions (around a few percent of an atomic unit). This review focuses on recent technical advancements and new classes of fragmentation experiments that have emerged over the past five years. These include: 1. **Multi-dimensional images in momentum space**: Provide unprecedented insights into the dynamics of single-photon-induced fragmentation of fixed-in-space molecules and their structure. 2. **High-intensity short-pulse laser-induced fragmentation**: Achievements in investigating atomic and molecular fragmentation using Reaction Microscopes. 3. **Two-electron reactions**: Maturation of the investigation of two-electron reactions, leading to fully differential cross sections (FDCS). 4. **Single ionization of atoms by ion-impact**: New insights and challenges at keV to GeV collision energies, with comprehensive sets of FDCS. The review also covers the kinematics of atomic fragmentation processes, imaging techniques, and target preparation methods, including supersonic gas-jets and magneto-optical traps (MOTRIMS). Finally, it discusses future potential and ongoing technical developments, such as the use of pulsed fields and advanced detector technologies.Recoil-ion and electron momentum spectroscopy is a rapidly advancing technique that measures the vector momenta of ions and electrons resulting from atomic or molecular fragmentation. Known as Reaction Microscopes, these instruments combine large solid angles (close to $4\pi$) with high momentum resolutions (around a few percent of an atomic unit). This review focuses on recent technical advancements and new classes of fragmentation experiments that have emerged over the past five years. These include: 1. **Multi-dimensional images in momentum space**: Provide unprecedented insights into the dynamics of single-photon-induced fragmentation of fixed-in-space molecules and their structure. 2. **High-intensity short-pulse laser-induced fragmentation**: Achievements in investigating atomic and molecular fragmentation using Reaction Microscopes. 3. **Two-electron reactions**: Maturation of the investigation of two-electron reactions, leading to fully differential cross sections (FDCS). 4. **Single ionization of atoms by ion-impact**: New insights and challenges at keV to GeV collision energies, with comprehensive sets of FDCS. The review also covers the kinematics of atomic fragmentation processes, imaging techniques, and target preparation methods, including supersonic gas-jets and magneto-optical traps (MOTRIMS). Finally, it discusses future potential and ongoing technical developments, such as the use of pulsed fields and advanced detector technologies.