This chapter presents Gauss’s law, a fundamental principle in electrostatics that provides an alternative and often simpler method for calculating electric fields, particularly for charge distributions exhibiting spatial symmetries. Building upon the foundational concepts of Coulomb’s law and the superposition principle introduced previously, the chapter first defines the flux of a vector field through a surface, both for planar and arbitrary closed surfaces. The core of the chapter is the formal introduction of Gauss’s law, presenting both its integral and differential forms. It highlights the profound relationship between the electric flux through a closed surface and the enclosed charge, demonstrating how this law is a direct consequence of Coulomb’s law. A significant emphasis is placed on leveraging symmetry arguments in electrostatics through Curie’s principle, which dictates that the symmetries of a charge distribution are reflected in its resulting electric field. This principle is then applied to analyze invariances under spatial translation, rotation, and mirror symmetries (and antisymmetries), providing powerful tools to constrain the direction and spatial dependence of the electric field. Practical applications of Gauss’s law are illustrated through detailed examples, such as determining the electric field generated by a uniformly charged sphere and an infinite plane of charge. The chapter also includes a proof of Gauss’s law and a summary of essential formulas, reinforcing its utility as a powerful analytical tool in electrostatics, especially when dealing with highly symmetric charge configurations.