Frailty is a common geriatric syndrome that embodies an elevated risk of catastrophic declines in health and function among older adults. Frailty is a condition associated with ageing with associated weakness, slowing, decreased energy, lower activity, and, when severe, unintended weight loss. As a population ages, a central focus of geriatricians and public health practitioners is to understand, and then beneficially intervene on, the factors and processes that put elders at such risk, especially the increased vulnerability to stressors (e.g. extremes of heat and cold, infection, injury, or even changes in medication) that characterizes many older adults. The syndrome of geriatric frailty is hypothesized to reflect impairments in the regulation of multiple physiologic systems, embodying a lack of resilience to physiologic challenges and thus elevated risk for a range of deleterious endpoints. The empirical assessment of geriatric frailty in individuals seeks to capture this or related features.