Electron Paramagnetic Resonance (EPR) is a specialized technique commonly used in chemistry, physics, and biology to study the electronic structure and properties of molecules, materials, and biological systems. The technique works by applying a magnetic field to a sample, which causes unpaired electrons in the molecule to align with the field. The resulting resonance interacts with microwaves, generating EPR signals that can be measured and interpreted to gain insights into the sample's properties. EPR is particularly useful for studying paramagnetic species with unpaired electrons, such as free radicals, transition metal complexes, and some biological molecules.