It is now customary to establish documentation cells within many special libraries to provide different types of information services to their clients. Whatever may be the organizational structure, the purpose is to accelerate the use of information through retrieval and dissemination process. These libraries and documentation cells often cater to the needs of people outside the organization, although their basic concerns are the requirements of host organizations.
In many countries, primarily at the instance of the UNESCO, national documentation centres have been set up which provide most of the services described. The Indian National Scientific Documentation Centre (INSDOC) and National Social Science Documentation Centre (NASSDOC) are examples of such national level centres in India: At the international level, several agencies of the United Nations function as international information centres e.g., the Information Unit attached to the Department of International, Economic and Social Affairs of the UN maintains the Development Information System, the services of which are available to all the member nations.