The Ising model is a mathematical model used in statistical mechanics to understand phase transitions, particularly in magnetic systems. It consists of discrete variables called "spins," which can take values of either +1 or -1. These spins are arranged on a lattice, and their interactions with neighboring spins determine the overall behavior of the system. In the Ising model, the energy of the system is influenced by the alignment of spins, with neighboring spins tending to align to minimize energy. This model helps explain phenomena such as ferromagnetism and critical points, making it a fundamental tool in the study of condensed matter physics.