ATM is acronym for Asynchronous Transfer Mode. ATM is a networking technology that transfer the data in form of cells of 53-bytes each. Out of the 53 byes, 5 are used for header and the other 48 are used for the data. The ATM technology was designed for the high speed transmission of data over network. Because of small size of cells, ATM equipment can be used to transfer large amounts of data over single connection. ATM technology also allows ISP to limit the bandwidth usage for each customer. Doing this improves the overall efficiency of the network.