Encapsulation means to cover or surround something in order to show or express the main idea or quality of it in a concise fashion. Encapsulation is a central part of modeling and designing systems in that it enables abstraction. Through encapsulation, the internal workings of any component part of a system can be concealed in order for it to reveal only the most essential properties and functionality required for its interaction with other components. In such a way encapsulation abstracts way the internal detail and complexity of a subsystem to enable the effective designing, functioning or vision of the whole system. Within systems design and modeling encapsulation enables a few key factors that are essential to the modeling of large and complex systems. Firstly it allows abstraction through what is called back boxing. Secondly, it enables the containment of interrelated elements and functions, restricting access to them and protecting them from outside interference.