A sphere in 3D space is the set of all points that are at a fixed distance (radius) from a central point (center).
If the center of the sphere is at \( M(x_0, y_0, z_0) \) and radius \( R \), then the equation is:
\[ (x - x_0)^2 + (y - y_0)^2 + (z - z_0)^2 = R^2 \]
