A social network is a system in which people or other entities are connected through relationships, interactions or shared affiliations. In computing and internet contexts, the term commonly refers to an online service that allows users to create profiles, establish connections, communicate and interact with content or with other users. The concept, however, is broader than a website or application because social networks can also be analysed mathematically as graphs consisting of nodes and relationships.
In an online social network, nodes commonly represent people, organisations or accounts, while edges represent relationships such as following, friendship, membership or interaction. Different services use different relationship models, including mutual friendships, one-way follows, subscriptions and group memberships. The fundamental purpose is to enable social connection and information exchange through a networked environment.
Online social networks generally provide mechanisms through which users identify themselves, discover other users and establish relationships. A profile can contain a username, photograph, biography, interests and other information, although the amount and visibility of such information vary. A user may follow another account without requiring reciprocal approval, or two users may become mutual contacts only after accepting a connection request. Groups, communities and pages can create additional relationship structures that are not simply person-to-person.
The network formed by these relationships can influence what information users encounter because platforms can use connection data as one input to content-distribution algorithms. Consequently, the structure of the social graph is not merely descriptive; it can affect discovery, communication and the visibility of content.
Social networking existed conceptually before the modern web because people have always formed networks through families, communities, organisations and professional relationships. Computer-mediated social networking developed through bulletin-board systems, mailing lists, online forums, chat systems and early community websites. Web-based social networking services became increasingly prominent as internet access expanded and web applications gained the ability to maintain user accounts, profiles and relationship databases. Later platforms introduced large-scale feeds, multimedia publishing, mobile applications and algorithmic recommendations.
The smartphone era made social networking continuously accessible through mobile devices, allowing users to create and consume content from almost anywhere with network connectivity. This evolution transformed social networking from relatively static online communities into highly dynamic systems combining communication, publishing, recommendation and commercial functions.
A social network is often represented using graph theory. A graph contains vertices representing entities and edges representing relationships. Networks can be directed, where a relationship has a direction such as one user following another, or undirected, where the relationship is considered mutual. Measures such as degree, centrality, density and clustering can be used to study network structure. In online systems, the graph can become extremely large and dynamic because users continuously create, remove or modify relationships. Interaction graphs can also be distinguished from explicit social graphs. Two users may not follow each other but may repeatedly comment on each other's content, producing an interaction relationship. Platforms can analyse these different forms of connection to personalise content and recommendations.
Social networks support many forms of communication and participation. Users can publish posts, exchange private messages, comment on content, participate in groups, share media, follow public figures or organisations and discover communities with shared interests. Professional social networks can focus on employment and business relationships, while other platforms may emphasise photographs, short videos, discussion, live broadcasting or community interaction.
The network structure enables information to spread through connections, meaning a post created by one user can potentially reach people far beyond the original audience when others share or interact with it. This network effect can make social networking useful for community building, collaboration, marketing and public communication, but it can also accelerate the spread of inaccurate or misleading information.
Social networks rely on data structures and infrastructure capable of representing enormous numbers of accounts, relationships and interactions. Databases and distributed systems store profiles, relationship information, posts, media metadata and interaction events. Search and recommendation systems help users discover accounts and content. Caching and content-delivery networks can improve the speed with which popular content is delivered to geographically distributed users. Moderation systems analyse content and behaviour to identify material that may violate platform rules or legal requirements. Identity and access-management systems control who can access accounts and resources. The technical architecture is therefore considerably more complex than the visible profile-and-friends interface suggests.
Social networks create both opportunities and risks. They can help geographically separated people maintain relationships, allow communities to organise and provide organisations with direct communication channels to audiences. Businesses can use them for customer engagement, recruitment, marketing and support. Researchers can analyse network structures to study communication and social behaviour, subject to appropriate ethical and privacy safeguards. At the same time, platforms can create privacy risks because relationship and behavioural data can reveal extensive information about users. Harassment, impersonation, fraud, coordinated manipulation, unwanted contact and harmful content can also occur. Algorithmic recommendation can amplify particular content patterns, while social comparison and notification mechanisms can affect how users interact with the service.
A social network should not be confused with social media, although the concepts overlap strongly. A social network emphasises relationships among people or entities, while social media is a broader category covering technologies and platforms through which users create, publish, share and interact with content. A messaging service can provide social-network functions without being primarily a public publishing platform. A discussion forum can support social interaction without implementing a conventional friend or follower graph. The term social network can also refer to the abstract network itself rather than to a specific company or application. Understanding these distinctions helps separate the underlying relationship structure from the broader technology and media ecosystem built around it.
