  N=1 curve is defined for four dimensional class S theory using
Cayley-Hamilton theorem for two commuting matrices. The curve consists of three
ingredients: 1: A set of N+1 degree N equations defining a curve; 2: a set of
constraints relating the coefficients in the curve; 3: a canonically defined
differential. We then extract from spectral curve various physical information
such as the space of moduli fields, chiral ring relations, full moduli space,
etc. Many examples are discussed, and the curve recovers the intricate vacua
structure which often involves highly non-trivial field theory dynamics such as
monopole condensation, dynamical generated superpotential, Seiberg duality,
etc.
