This course examines linear and nonlinear phenomena that exist in the universe through mathematical models, especially through systems of ordinary differential equations. Lectures will involve students in understanding planar linear systems, plane and phase portraits, system equilibrium points, stability analysis, planar nonlinear systems, high-dimensional nonlinear systems, linearization, eigenvalue analysis, and bifurcation. Methods for solving the system are carried out analytically, geometrically, topologically and numerically using software assistance.