Old age frailty has no consensus definition so far, but it is commonly operationalised as a physical phenotype consisting of weight loss, exhaustion, physical inactivity, slowness and weakness. Phenotypic frailty is characterised by reductions in the reserves of various organ systems and impaired stress tolerance, with increased risk of important endpoints: disability, morbidity and death. The development of sarcopenia is often a conspicuous characteristic, and cognitive decline is a frequent companion; frail individuals may also be obese. According to epidemiological studies, phenotypic frailty can be discerned in 5 to 10% of community-living older individuals, prefrailty even in 20 to 40%. To prevent deterioration and development of disability, prefrail and frail individuals should be recognised in time to target interventions in primary care. There is also an emerging interest in various specialties to recognise frailty to better adjust treatments and prevent complications. Multidomain and multisystem interventions are probably the best options for prevention and treatment, but at the moment best evidence is available from exercise. Various pharmacological treatments are being investigated for frailty components, but trial data are scarce so far. In advanced frailty, treatment is moved to appropriate geriatric palliative care.