Differential equations are the primary method for analyzing the dynamics of more or less complex systems. They are also one of the main tools for implementing models of biological systems. Therefore, they are one of the most interesting fields of mathematics. We will briefly examine, without mathematical rigor, how to solve the simplest types of differential equations, such as first- and second-order linear equations. The concept of exact differential equations and their solutions will also be briefly discussed. Finally, there will be a brief discussion of partial differential equations.