The *Gaia* mission has significantly advanced the study of binary stars, providing high-precision astrometry for over a billion stars in the Milky Way. Binary stars are crucial for understanding stellar mass, radius, and evolutionary models, as well as for explaining phenomena like supernovae and gamma-ray bursts. *Gaia* has enabled a more accurate census of binary populations and the discovery of rare objects, particularly wide binaries (separations ≥ 100 au). The mission's data, especially in DR3, have improved the detection of astrometric and radial velocity orbits, and have provided insights into binaries containing non-accreting compact objects. However, *Gaia* has limitations in resolving very close binaries and detecting some rare cases, requiring follow-up with ground-based observations. Future improvements with *Gaia* DR4 are expected to enhance these capabilities. The mission has also revealed new insights into the demographics of wide binaries, including their separation distributions, eccentricities, and mass ratios. Studies have shown that wide binaries can have different formation mechanisms, and that their properties vary with metallicity and stellar mass. *Gaia* has also contributed to the discovery of hierarchical triples and quadruples, and has provided data for testing modified gravity theories. The mission's data have been used to measure the mass-luminosity relation and to study the effects of binary interactions on stellar evolution. Overall, *Gaia* has revolutionized the study of binary stars, offering new perspectives on their formation, evolution, and impact on the universe.The *Gaia* mission has significantly advanced the study of binary stars, providing high-precision astrometry for over a billion stars in the Milky Way. Binary stars are crucial for understanding stellar mass, radius, and evolutionary models, as well as for explaining phenomena like supernovae and gamma-ray bursts. *Gaia* has enabled a more accurate census of binary populations and the discovery of rare objects, particularly wide binaries (separations ≥ 100 au). The mission's data, especially in DR3, have improved the detection of astrometric and radial velocity orbits, and have provided insights into binaries containing non-accreting compact objects. However, *Gaia* has limitations in resolving very close binaries and detecting some rare cases, requiring follow-up with ground-based observations. Future improvements with *Gaia* DR4 are expected to enhance these capabilities. The mission has also revealed new insights into the demographics of wide binaries, including their separation distributions, eccentricities, and mass ratios. Studies have shown that wide binaries can have different formation mechanisms, and that their properties vary with metallicity and stellar mass. *Gaia* has also contributed to the discovery of hierarchical triples and quadruples, and has provided data for testing modified gravity theories. The mission's data have been used to measure the mass-luminosity relation and to study the effects of binary interactions on stellar evolution. Overall, *Gaia* has revolutionized the study of binary stars, offering new perspectives on their formation, evolution, and impact on the universe.