Circuit switching was the first information transform mode which was used for telephone networks. It is more efficient for transport real time services which requires quality of service qurantees in terms of delay and loss. In fact,TDM doesnot offers no delay except for switching latency and no packet losses. But on the otherhand, circuit switching was found inefficient for the transport of bursty traffic.
For bursty traffic packet switching was developed. The packet switching offers transport of bursty traffic but no quality of services. It is essentially a best effort switching technique where network will make attempt to trasfer every packet.

ATM switching is the technology which was developed by merging the concept of both packet as well as circuit switching. It has the various advantages
1. It offers quality of services like circuit switching.
2. It offers the statistical multiplexing like pacet switching.