Inspired by empirical studies of networked systems such as the Internet, social networks, and biological networks, researchers have in recent years developed a variety of techniques and models to help us understand or predict the behavior of these systems. Here we review developments in this field, including such concepts as the small-world effect, degree distributions, clustering, network correlations, random graph models, models of network growth and preferential attachment, and dynamical processes taking place on networks.

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The Structure and Function of Complex Networks

Similarity breeds connection. This principle—the homophily principle—structures network ties of every type, including marriage, friendship, work, advice, support, information transfer, exchange, comembership, and other types of relationship. The result is that people's personal networks are homogeneous with regard to many sociodemographic, behavioral, and intrapersonal characteristics. Homophily limits people's social worlds in a way that has powerful implications for the information they receive, the attitudes they form, and the interactions they experience. Homophily in race and ethnicity creates the strongest divides in our personal environments, with age, religion, education, occupation, and gender following in roughly that order. Geographic propinquity, families, organizations, and isomorphic positions in social systems all create contexts in which homophilous relations form. Ties between nonsimilar individuals also dissolve at a higher rate, which sets the stage for the formation of niches (localize...

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Birds of a Feather: Homophily in Social Networks

Social network sites SNSs are increasingly attracting the attention of academic and industry researchers intrigued by their affordances and reach This special theme section of the Journal of Computer-Mediated Communication brings together scholarship on these emergent phenomena In this introductory article, we describe features of SNSs and propose a comprehensive definition We then present one perspective on the history of such sites, discussing key changes and developments After briefly summarizing existing scholarship concerning SNSs, we discuss the articles in this special section and conclude with considerations for future research

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1083-6101.2007.00393.x

Social Network Sites: Definition, History, and Scholarship

Examines whether the positive association between social support and well-being is attributable more to an overall beneficial effect of support (main- or direct-effect model) or to a process of support protecting persons from potentially adverse effects of stressful events (buffering model). The review of studies is organized according to (1) whether a measure assesses support structure (the existence of relationships) or function (the extent to which one's interpersonal relationships provide particular resources) and (2) the degree of specificity (vs globality) of the scale. Special attention is given to methodological characteristics that are requisite for a fair comparison of the models. It is concluded that there is evidence consistent with both models. Evidence for the buffering model is found when the social support measure assesses the perceived availability of interpersonal resources that are responsive to the needs elicited by stressful events. Evidence for a main effect model is found when the support measure assesses a person's degree of integration in a large social network. Both conceptualizations of social support are correct in some respects, but each represents a different process through which social support may affect well-being. Implications for theories of social support processes and for the design of preventive interventions are discussed.

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Stress, social support, and the buffering hypothesis.

Imagined communities: Reflections on the origin and spread of nationalism

Community ties with friends and relatives are a principal means by which people and households get supportive resources. Quantitative and qualitative data from the second East York study are used to evaluate six potential explanations of why different types of ties provide different kinds of supportive resources: tie strength, contact, group processes, kinship,network members' characteristics, and similarities and dissimilarities between network members in such characteristics. Most relatioships provide specialized support. The kinds of support provided are related more to characteristics of the relationship than to characteristics of the network members themselves. Strong ties provide emotional aid, small services, and companionship. Parents and adult children exchange financial aid, emotional aid, large services, and small services. Physically accessible ties provide services. Women provide emotional aid. Friends, neighbors, and siblings make up about half of all supportive relationships. The ensemble o...

Different Strokes from Different Folks: Community Ties and Social Support

How does the Internet affect social capital? Do the communication possibilities of the Internet increase, decrease, or supplement interpersonal contact, participation, and community commitment? This evidence comes from a 1998 survey of 39,211 visitors to the National Geographic Society Web site, one of the first large-scale Web surveys. The authors find that people's interaction online supplements their face-to-face and telephone communication without increasing or decreasing it. However, heavy Internet use is associated with increased participation in voluntary organizations and politics. Further support for this effect is the positive association between offline and online participation in voluntary organizations and politics. However, the effects of the Internet are not only positive: The heaviest users of the Internet are the least committed to online community. Taken together, this evidence suggests that the Internet is becoming normalized as it is incorporated into the routine practices of everyday ...

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Does the Internet Increase, Decrease, or Supplement Social Capital? : Social Networks, Participation, and Community Commitment

The Community Question has set the agenda for much or much of sociology. It is the question of how large-scale social systemic divisions of labor affect the organization and content of primary ties. Network analysis is proposed as a useful approach to the Community Question, because, by focusing on linkages, it avoids the a priori confinement of analysis to solidary groupings and territorial units. Three contentions about the Question are evaluated: arguments that Community is Lost, Saved or Liberted. Data are presented about the structure and use of the "intimate" networks of 845 adult residents of East York, Toronto. Intimate networks are found to be prevalent, composed of both kin and nonkin, nonlocal, asymmetric, and of sparse density. Help in dealing with both emergencies and everyday matters is available from almost all intimate networks, but from only a minority of intimate ties. The data provide broad support for the Liberated argument, in conjunction with some portions of the Saved argument.

The Community Question: The Intimate Networks of East Yorkers

Computer networks are social networks. Social affordances of computer-supported social networks – broader bandwidth, wireless portability, globalized connectivity, personalization – are fostering the movement from door-to-door and place-to-place communities to person-to-person and role-to-role communities. People connect in social networks rather than in communal groups. In-person and computer-mediated communication are integrated in communities characterized by personalized networking.

Les reseaux informatiques sont des reseaux sociaux. Les possibilites sociales qu’offrent les reseaux sociaux informatises – bande passante plus large, portabilite sans fil, connectivite mondiale, personnalisation – sont en train de favoriser le passage de communautes de porte-a-porte et de lieu-a-lieu vers des communautes d’individu-a-individu et de role-a-role. Ainsi, les gens se lient davantage dans des reseaux sociaux que dans des collectivites. Les communications directes et via l’informatique sont integrees dans des communautes caracterisees par un maillage personnalise.

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Physical Place and Cyberplace: The Rise of Personalized Networking

When computer networks link people as well as machines, they become social networks. Such computer-supported social networks (CSSNs) are becoming important bases of virtual communities, computer-supported cooperative work, and telework. Computer-mediated communication such as electronic mail and computerized conferencing is usually text-based and asynchronous. It has limited social presence, and on-line communications are often more uninhibited, creative, and blunt than in-person communication. Nevertheless, CSSNs sustain strong, intermediate, and weak ties that provide information and social support in both specialized and broadly based relationships. CSSNs foster virtual communities that are usually partial and narrowly focused, although some do become encompassing and broadly based. CSSNs accomplish a wide variety of cooperative work, connecting workers within and between organizations who are often physically dispersed. CSSNs also link teleworkers from their homes or remote work centers to main organi...

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Barry Wellman

Papers

Different Strokes from Different Folks: Community Ties and Social Support

Does the Internet Increase, Decrease, or Supplement Social Capital? : Social Networks, Participation, and Community Commitment

The Community Question: The Intimate Networks of East Yorkers

Physical Place and Cyberplace: The Rise of Personalized Networking

Computer Networks as Social Networks: Collaborative Work, Telework, and Virtual Community