**Abstract**

The concept of frailty is frequently mentioned in studies related to the elderly population. Frailty in the elderly is considered a relevant dimension of quality of life. The concept of frailty has grown in importance because of a need to evaluate the health status of older persons and a need to prevent or at least delay late-life disability and total dependence on self-care. There is to date no clear consensus regarding the definition of frailty; some definitions have been proposed, each with their own strengths and weaknesses. Just as conceptual disagreements arise about what frailty means, there are also disagreements about how to assess it. However, as researchers deepen the concept of frailty and the way to operationalize it, scales and inventories appear that allow us to have a more precise idea of the state of frailty. This aspect is extremely important because assistance strategies may depend on it. One of the most cited aspects is the assessment of the need to provide palliative care. In this chapter, we intend to review the concepts of frailty, operationalization strategies and assessment tools and clarify some ideas from the debate on what frailty is.

**Keywords:** cognition, dependence, elderly, frailty, functionality
