Multiphoton microscopy is a non-linear optical imaging technique that allows for deep-tissue imaging with high resolution and minimal photodamage. It involves the simultaneous absorption of two or more photons, typically using infrared laser light, to excite fluorescent molecules within a sample. This technique is commonly used in biological and medical research to study living tissues, such as the brain, due to its ability to penetrate deep into samples without causing as much photo damage as traditional microscopy techniques. Multiphoton microscopy has revolutionized our understanding of biological processes and has led to important discoveries in fields such as neuroscience, developmental biology, and cancer research.