Social support is the perception and actuality that one is cared for, has assistance available from other people, and, most popularly, that one is part of a supportive social network. These supportive resources can be emotional (e.g., nurturance), informational (e.g., advice), or companionship (e.g., sense of belonging); tangible (e.g., financial assistance) or intangible (e.g., personal advice). Social support can be measured as the perception that one has assistance available, the actual received assistance, or the degree to which a person is integrated in a social network. Support can come from many sources, such as family, friends, pets, neighbors, coworkers, organizations, etc.

Social support is studied across a wide range of disciplines including psychology, communications, medicine, sociology, nursing, public health, education, rehabilitation, and social work. Social support has been linked to many benefits for both physical and mental health, but "social support" (e.g., gossiping about friends) is not always beneficial.

Social support theories and models were prevalent as intensive academic studies in the 1980s and 1990s, and are linked to the development of caregiver and payment models, and community delivery systems in the US and around the world. Two main models have been proposed to describe the link between social support and health: the buffering hypothesis and the direct effects hypothesis. Gender and cultural differences in social support have been found in fields such as education "which may not control for age, disability, income and social status, ethnic and racial, or other significant factors".

Social support can be categorized and measured in several different ways.

There are four common functions of social support:

Researchers also commonly make a distinction between perceived and received support. Perceived support refers to a recipient's subjective judgment that providers will offer (or have offered) effective help during times of need. Received support (also called enacted support) refers to specific supportive actions (e.g., advice or reassurance) offered by providers during times of need.

Furthermore, social support can be measured in terms of structural support or functional support. Structural support (also called social integration) refers to the extent to which a recipient is connected within a social network, like the number of social ties or how integrated a person is within his or her social network. Family relationships, friends, and membership in clubs and organizations contribute to social integration. Functional support looks at the specific functions that members in this social network can provide, such as the emotional, instrumental, informational, and companionship support listed above. Data suggests that emotional support may play a more significant role in protecting individuals from the deleterious effects of stress than structural means of support, such as social involvement or activity.

These different types of social support have different patterns of correlations with health, personality, and personal relationships. For example, perceived support is consistently linked to better mental health whereas received support and social integration are not. In fact, research indicates that perceived social support that is untapped can be more effective and beneficial than utilized social support. Some have suggested that invisible support, a form of support where the person has support without his or her awareness, may be the most beneficial. This view has been complicated, however, by more recent research suggesting the effects of invisible social support – as with visible support – are moderated by provider, recipient, and contextual factors such as recipients' perceptions of providers' responsiveness to their needs, or the quality of the relationship between the support provider and recipient.