A system landscape comprises the enterprise information systems of a company and their connections. Usually, there are many in large companies, even more if also smaller individual application programs are taken into account. The systems must work together and therefore need to be integrated. We look at the difficulties that arise in integration, as well as approaches to solve them. For documentation, but also for system administration and data exchange between the systems, system landscapes are depicted in a model. In addition to common box diagrams, there are digital versions.