A Gaussian surface is a surface in a three-dimensional space used in Gauss’ law to calculate the flux of a vector field. If the electrical field is constant, the electrical flux can be calculated by multiplying the value of the electrical field by the area of the Gaussian surface.
The preferred Gaussian surface is one where for every point on the surface, the component of the electric field along the normal vector is constant. This is preferred because the calculation does not require difficult integration and the resulting constants can be removed from the integral. The majority of calculations that utilize Gaussian surfaces start with implementing Gauss’ law.