A social network is a social structure made of nodes (which are generally individuals or organizations) that are tied by one or more specific types of interdependency, such as values, visions, idea, financial exchange, friends, kinship, dislike, conflict, trade, web links, sexual relations, disease transmission (epidemiology), or airline routes. The resulting structures are often very complex.

• Social engineering (political science), efforts to influence popular societies on a large scale.
• Social engineering (security), the practice of obtaining confidential information by manipulating users.
• Social Engineering (sociology), efforts to fix a sociological problem in a society

Social capital, referring to connections within and between social networks, is a core concept in business, economics, organizational behaviour, political science, public health, sociology and natural resources management. Though there are in fact a variety of inter-related definitions of this term, which has been described as "something of a cure-all"[1] for the problems of modern society, they tend to share the core idea "that social networks have value. Just as a screwdriver (physical capital) or a college education (human capital) can increase productivity (both individual and collective), so too social contacts affect the productivity of individuals and groups"

"social capital" refers to features of social organization such as networks, norms, and social trust that facilitate coordination and cooperation for mutual benefit.