Two-dimensional systems refer to physical or mathematical models that exist in two dimensions, typically represented by a flat plane. In these systems, objects or phenomena can be described using only two coordinates, such as length and width, without considering height. Examples include graphs, maps, and certain types of materials like graphene, which exhibit unique properties due to their two-dimensional structure. In physics, two-dimensional systems are often studied to understand complex behaviors in a simplified context. For instance, quantum mechanics can be applied to two-dimensional electron gases, revealing insights into electronic properties and interactions. These systems help researchers explore fundamental concepts while minimizing variables.