A social networking service is an online service, platform, or site that focuses on facilitating the building of social networks or social relations among people who, for example, share interests, activities, backgrounds, or real-life connections. A social network service consists of a representation of each user (often a profile), his/her social links, and a variety of additional services. Most social network services are web-based and provide means for users to interact over the Internet, such as e-mail and instant messaging. Online community services are sometimes considered as a social network service, though in a broader sense, social network service usually means an individual-centered service whereas online community services are group-centered. Social networking sites allow users to share ideas, activities, events, and interests within their individual networks.

The main types of social networking services are those that contain category places (such as former school year or classmates), means to connect with friends (usually with self-description pages), and a recommendation system linked to trust. Popular methods now combine many of these, with Facebook, Google+ and Twitter widely used worldwide, The Sphere (luxury network), Nexopia (mostly in Canada);Bebo,VKontakte, Hi5, Hyves (mostly in The Netherlands), Draugiem.lv (mostly in Latvia), Ask-a-peer (career oriented), StudiVZ (mostly in Germany), iWiW (mostly in Hungary), Tuenti (mostly in Spain), Nasza-Klasa (mostly in Poland), Tagged, XING,Badoo and Skyrock in parts of Europe;Orkut and Hi5 in South America and Central America; and Mixi, Orkut, Wretch, renren and Cyworld in Asia and the Pacific Islands and Facebook, Google+, Twitter and LinkedIn are very popular in India and Pinterest is also a social networking site which is used in India.

A network service is a service hosted on a computer network. Network services provide some functionality for members or users of the network. Services are usually based on a defined service protocol. Network services are hosted by servers to provide shared resources to client computers. The service software is often referred to as a port, daemon, or listener. A specific kind of service is often mapped to a specific port number for the underlying transmission protocol (e.g. Internet Protocol, Transmission Control Protocol, User Datagram Protocol).

An examples of a network services would include Domain Name System (DNS), DHCP, NetBIOS, and HTTP.

Network services are configured on corporate local area networks to ensure security and user friendly operation. They help the LAN run smoothly and efficiently. Corporate LANs use network services such as DNS (Domain Name System) to give names to IP and MAC addresses (people remember names like “nm.lan” better than they remember numbers like “210.121.67.18”), and DHCP to ensure that everyone on the network has a valid IP address.

A social network is a social structure made up of a set of actors (such as individuals or organizations) and the dyadic ties between these actors. The social network perspective provides a clear way of analyzing the structure of whole social entities. The study of these structures uses methods of social network analysis to identify local and global patterns, locate influential entities, and examine network dynamics.

Social networks and the analysis of them is an inherently interdisciplinary academic field which emerged from social psychology, sociology, statistics, and graph theory. Georg Simmel authored early structural theories in sociology emphasizing the dynamics of triads and "web of group affiliations."Jacob Moreno is credited with developing the first sociograms in the 1930s to study interpersonal relationships as structures in which people were points and the relationships between them were drawn as connecting lines. These approaches were mathematically formalized in the 1950s and theories and methods of social networks became pervasive in the social and behavioral sciences by the 1980s. Social network analysis is now one of the major paradigms in contemporary sociology, and is also employed in a number of other social and formal sciences. Together with other complex networks, it forms part of the nascent field of network science.