Based on the above, this drink is a key component of the Mediterranean diet, associated with a lower incidence of cardiovascular diseases, some forms of cancer, and other disorders related with oxidative stress. In this paper, we review and discuss the main benefits attributed to its moderate consumption, examine the phenolics composition, the chemical characteristics of its major antioxidant components, and their relationship with its biological activity. We also summarize the main methodologies used for their identification and quantification, and the measurements of antioxidant activity.