Phonon transport is a branch of condensed matter physics that studies the propagation of phonons, which are quantized vibrations or oscillations in a crystalline lattice structure. Phonons play a crucial role in determining the thermal conductivity of materials, as they are responsible for carrying heat through a material by transferring energy between vibrating atoms. Understanding phonon transport is essential for designing and developing materials with specific thermal properties, such as high thermal conductivity for efficient heat dissipation in electronics or low thermal conductivity for insulation applications. Researchers in this field use theoretical models, computational simulations, and experimental techniques to study the behavior of phonons in different materials and environments.