In mathematics, a set of simultaneous equations, also known as a system of equations or an equation system, is a finite set of equations for which common solutions are sought. An equation system is usually classified in the same manner as single equations, namely as a:

• System of linear equations,
• System of nonlinear equations,
• System of bilinear equations,
• System of polynomial equations,
• System of differential equations, or a
• System of difference equations