Metropolitan Area Networks: These type of networks generally cover specific metropolitan area and provide to them all the services. 

Wide Area Networks (WANs):

Wide Area Networks (WANs) are private networks linking equipment at several different sites and have much in common -with conventional large scale data networks. 

In configuring a network to communicate information the focus is on minimising costs while maintaining the desired performance (or minimum desired quality) standards depend on the nature of the information to be sent. In the case of voice, quality is measured by word intelligibility or articulation index. For video, the Television Allocations Study Organisation has adopted the TASO grades ranging from excellent to poor that specify the degree of subjective acceptability of the picture displayed to viewing audiences. For both voice and video, the corresponding quantified measure of quality, signal-to-noise ratio, is used as a technical design parameter. For digital information, say from one computer to the other the quality of the transmission is expressed as the number of bit 'errors', a appearing as '0' or vice versa, that occur as a fraction of the total number of bits sent. 

Along with performance requirements, it is necessary to choose the channel bandwidth for analog transmission. The transmission speed of digital signals is also referred to as data rate or bit rate. These factors partly determine coat. Therefore, depending on whether the  transmission is from one point to another, one point to several, or several points to a central point, a network is designed. The simplest 'network' might involve just two stations (point to point) linked for example, to transfer data from one computer to another, or it might be a complicated system where several stations are connected to a local node, several local nodes connected to a central node, and so on in hierarchical fashion. 

Developments in network technology include the increasing use of computers to control switching and information flow, most significant is the modernisation of the public network so that voice and data can be carried over a single network. This type of single network is referred to as an Integrated Services Digital Network (ISDN).