1. Open System Interconncetion Reference Model (OSI model)

Physical Layer: Network interface controller (网卡), ethernet hub (集线器), network switch, transmission medium. It converts digital bits to electrical, radio or optical signals. Voltage characteristics are defined.

Datalink Layer: Medium access control (MAC) layer, logical link control (LLC) layer. Correct errors that may occur in physical layers.

Network Layer: Provides to transfer packets from node to node. (IP)

Transport Layer: Provides to transfer variable length data sequences from source host to destination host. (TCP, UDP)

Session Layer: Creates the setup, controls the conntections and ends the teardown between two or more computers.

Presentation Layer: Establish data formatting and data translation.

Application Layer: Applications that implements a component of communication between client and server.

2. IP Address

IP address is a 32 bits address according to IPv4 standard. Domain name system (DNS) are proposed to overcome the difficulty of remebering this address.

3. TCP/IP & UDP

Transmission control protocol/Internet Protocol (TCP/IP). For simplicity, the last three layers in OSI model are merge into application layer. In fact, it includes many other protocols like FTP, SMTP, etc.

User datagram protocol (UDP) provides service without building connections.

4. HTTP/HTTPS

Hyper-text transfer protocol. ’s’ means secure where Secure Socket Layer (SSL) encryption is added.

5. Socket

Socket is an abstract of node in the network.