Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A quartic plane curve is a plane curve of the fourth degree. It can be defined by a quartic equation: Ax4 + By4 + Cx3y + Dx2y2 + Exy3 + Fx3 + Gy3 + Hx2y + Ixy2 + Jx2 + Ky2 + Lxy + Mx + Ny + P = 0. This equation has fifteen constants. However, it can be multiplied by any non-zero constant without changing the the curve. In mathematics, a plane curve is a curve in a Euclidian plane (cf. space curve). The most frequently studied cases are smooth plane curves (including piecewise smooth plane curves), and algebraic plane curves.