OSI refrence model proposed by ISO.
we care about OSI because
1. It filters all the network communication into the small and simple component.
2. It allows vendor development through the standard network components as well as various types of network hardware and software to communicate.
3 and the changes in one layer affecting to the another layer, so it does not hamper development.
Main purpose to create this model that it provides a framework to implement and developed the network components and internetworking scheme as well as all the vendors developed there produt under a single standard.