Open System Interconnection (OSI)

7 layers:

1)     Physical layer: physical devices like NIC, HUB, wore falls on this layer. Data goes to wore for electrical signal propagation.

2)     Data- link: devices like switch, bridge falls on this layer. Protocols like Ethernet, token ring are the protocol running on this layer.

3)     Network: devices like router and manageable switch works in network layer. Network layer is mainly responsible to find the way for data transfer and move the data from one network to another.

4)     Transport: it is responsible for data delivery from source to destination.
TCP – Transmission Control Protocol. UDP- User Datagram Protocol

5)     Session: it is used to create, manage and terminate session for a link.

6)     Presentation: deals with the coding and encoding or data presentation. All software keeps their data under specific format, data encryption and decryption falls under this layer. E.g. .doc, .ppt, .bat etc.

7)     Application: applications and methods to access the application falls under this layer. E.g. HTTP, FTP, SMTP.