**1. Introduction**

Despite each biography's heterogeneity and the diverse trajectories in the life course, social networks are central in life experience. This is particularly reflected in the characteristics of social support in the last stages of the life cycle.

In later life, family relationships emerge as the core of social networks [1, 2]. The relevance of family in social networks' structure is evident, in general, but more relevant when addressing old ages. The family ties frequently determine the network type, either by its dominance, by the proportion in the network size, or by its absence.

The older population's social networks' typologies aggregate key commonality features, such as network size, network composition (proportion and type of family ties), marital status, frequency of contacts, and community participation or engagement [3]. These typologies allow organizing knowledge about social support, intergenerational relationships, psychosocial needs, social risk, and wellbeing, providing guidelines that allow anticipating the diversity of aging trajectories.

Beyond the relevance of family-centered networks, they also emerge as important for wellbeing in old age, the restricted and the diverse social, personal networks. These last two network types are associated with antagonistic social support and wellbeing effectiveness features [2, 3]. Restricted and diverse networks are also predictors of health, mental health, and social participation, as key promotors of wellbeing.

Family intergenerational relationships constitute social support sources pointed out as primordial informal resources when evaluating old-age support systems [4]. However, changes in contemporary societies' family structures have complex and multidimensional implications in our lives and provision systems. Families' availability as a primary support source depends on family structure, lifestyle, gender, individual or familial choices, work-life balance, or care burden.

Nowadays, childlessness is statically less exceptional [5] and constitutes an emerging challenge for informal and formal support systems. Familistic or nonfamilistic cultures represent different demands and expectations on informal support and social care, challenging generations' relations. In old age, from a pessimistic perspective, childlessness interrupts the normative commitment to reciprocity expected between generations, leaving a void difficult to fulfill. In an optimistic perspective, having a life path marked by not having children allows people to explore relational dimensions differently.

The present chapter focus on the social network types and features in old age. Family-centered networks, restricted, and diverse are analyzed and discussed concerning wellbeing and the psychosocial risks associated with the aging process. The emphasis on family ties and interpersonal relationships between generations are approached, focusing on social networks' dominant characteristics and the challenges concerning informal and formal social support within contemporary societies.
