Traditionally used as a descriptive term, frailty is now a recognized medical syndrome identifying individuals with decreased physiologic reserve. Frailty is characterized by diminished strength, endurance, and reduced physiologic function. Several valid frailty screening tools exist in the literature, and these measures have been used to relate frailty to outcomes important to the older patient with cancer. Frail adults are at increased risk of adverse surgical outcomes and early findings suggest that frailty predicts poor chemotherapy tolerance. While much research is needed to explore the biologic relationships between frailty and cancer, there is an urgent need to implement frailty screening and management into the care of the older patient with cancer in order to improve outcomes in this vulnerable subset. The purpose of this paper is to provide an introduction of frailty to oncologists including a review of the definition, frailty screening tools, its clinical relevance to older patients with cancer, and a brief guide to frailty management.