Uniform nuclear matter is an idealized system used to study saturation, compressibility, symmetry energy, and phase structure. Its equation of state, $$P(\rho, Y_p)$$ or equivalently $E/A(\rho, Y_p)$, is crucial for finite nuclei, heavy-ion collisions, and neutron stars.

Neutron stars probe matter at densities beyond those in ordinary nuclei, where many-body forces, hyperons, superfluidity, and possible phase transitions may appear. Observations of masses, radii, tidal deformabilities, and cooling are now essential constraints on nuclear equations of state.

Relativistic and intermediate-energy heavy-ion collisions access compressed and heated nuclear matter. Measurements of flow, particle production, and collective observables help infer the equation of state and transport properties of dense matter.