Interconnecting several devices can present problems because of compatibility problems. In order to facilitate communications between different devices the International Standard Organization (ISO) devised a ISO/OSI model to be used for standardization for Open System Interconnection (OSI).
A communication link between items of digital equipment is defined in terms of:
* protocol and
* user standards.
Each layer is self contained and only deals with the interfaces of the layer immediately above and below. It performs its tasks and transfers its results to the layer above or the layer below.
It enables manufacturers of products to design products operable in a particular layer that will interface with the hardware of other manufacturers.