Packet switching VS Circuit switching

Packet switching

1. Data to be transmitted is divided into fix-sized blocks called 'packets' or 'datagrams.
2. These packets are then transmitted through the network independently of each other.
3. The packets may take different routes between the two end points and arrive in a non-sequential order.
4. The packets are reorganized by the recipient to get the correct data.
5. Each network link will transport packets from many different communication sessions between many hosts (That means that packets of different communication sessions may share the same link. In another words, the link is not dedicated!)

Circuit switching

1. A dedicated communication channel or circuit is established to enable communication between two network nodes or end-points. (dedicated means the communication channel or circuit is made only for this particular communication. It is not shared by others.)
2. The dedicated link guarantees communication at a constant bit-rate
3. The earliest example of circuit switching was the analogue telephone network. A connection from the calling telephone established a connection to the telephone exchange by dialing the number. The connection was retained for the duration of the call and then released when the telephone call hung up. Even if no data exchange is taking place, the connection remains until released. The connection remains protected form other potential user of the network, even though no communication may be taking place. (This is why making a phone call is much expensive than making a Wechat voice call. More about this, refer to: VoIP)