  Fracton emerges from strongly interacting many-body systems whose
excitations, referred to as sub-dimensional particles, have restricted mobility
or kinetic motions. These entities have garnered significant interest due to
their interdisciplinary implications spanning topological quantum codes,
quantum field theory, emergent gravity, quantum information, and more,
revealing unique nonequilibrium behaviors such as nonergodicity and glassy
dynamics. This review presents a structured and educational overview of fracton
phenomena, specifically focusing on gapless fracton liquids. Noteworthy for
their compressibility and gapless excitations, fracton liquids facilitate
collective modes reminiscent of those gauge fluctuations found in Maxwell's
electromagnetic framework. However, they are distinct due to an additional
higher-moment conservation law that restricts the mobility of individual
charges and monopoles. Our exploration begins with the theoretical foundation
of 3D fracton liquids, presenting a variety of emergent symmetric tensor gauge
theories and reviewing their equilibrium and dynamic properties. Following this
theoretical groundwork, we discuss the material realization of various fracton
liquids in Yb-based breathing pyrochlore lattices, close-packed tiling
structures and other synthetic quantum matter platforms. Additionally, we
introduce a general protocol to foster and manipulate emergent fracton spin
liquids in the realm of frustrated magnetism.
