Beam-splitting is a technique used in optics to divide a single input beam of light into multiple output beams. This can be done using various methods such as using a partially reflective mirror, a beamsplitter cube, or a diffraction grating. Beam-splitting is commonly used in applications such as interferometry, microscopy, and telecommunications. It allows for the manipulation and control of the intensity and direction of light beams, enabling the creation of complex optical setups and systems.