The Range of Network Services  

The range of services provided by many resource sharing networks include storage and retrieval of data such as factual, physical and bibliographic data, document ordering and delivery services, general computer and support of group communication and decision making. The most widely used networks can be described by four major types of services. They are: 

1. shared cataloguing;
2. on-line reference; 
3. shared circulation; 
4. Interlibrary loan. 

Of course, cataloguing networks are by far popular type and are often cited as examples of computer applications to library services. Even though library network systems have undergone major development since 1960s and 1970s, the central objectives of networking remain-constant. They are: 

1. To reveal the contents of large number of libraries, especially through accessibility of catalogue databases, using OPAC interfaces; 
2. To make resources shown in these catalogue databases available to individual libraries and user when and where they are needed; 
3. To share the expense and the work involved in creating catalogue database through the exchange of records and associated activities. 
4. Additional functions that might be fulfilled by networks.    
5. distribution and publication of electronic journals and other electronic documents; 
6. end-user access to other databases, such as those available on the online hosts and CD-ROM; 
7. value-added service such as electronic mail, directory services and file transfer; 
8. exchange of bibliographic and authority records usually in MARC format. 

If we follow closely the evolution of library networks, it will be observed that in the beginning, networks were established with limited and well-defined objectives. As the use of networking has become more pervasive due to the easy availability of' the infrastructure, the scope of the networks became broader and a number of interconnected consortia of networks and members has become possible. This has enabled the end-user to choose more than one route through the maze of networks in order to locate a given document or piece of bibliographic information. In other words, access barriers have become less and less. This has resulted in the establishment of key agencies in library networking. These key agencies may be grouped into two main categories. 

1. Large national libraries or centralised cataloguing services which create large bibliographic databases and also occasionally provide the document delivery facility; 
2. Cooperatives set up by groups of libraries, who feel that they and their users can profit by resource sharing through inter library loans and also by participation in the creation of a union catalogue.