The OSI reference model
& TCP/IP reference model
Although the protocols associated with the OSI model are rarely used any more,the model itself is general and still valid,and the features at each layer are still very important.
The TCP/IP model, the model itself is not of much use but the protocol are widely used.
OSI model is based on ISO as a first step toward international standardization of the protocols used in various layers.It deals with connecting open system-systems that are open for communication with other systems. The OSI model has 7 layers.
To be continued..