The aim of this synthesized literature review is to provide an overview of patient-reported outcomes (PROs), a term we use to refer to both health outcomes reported directly by patients, and the tools used for their collection and measurement. Developed from the 2000s onwards, PROs have multiplied as their uses have diversified. We review approximately 50 articles authored by clinical researchers, public health physicians, and to a lesser extent, health economists, as well as approximately 10 practice guidelines distributed by public agencies, research consortia, and think tanks that develop PROs. The overview begins with descriptions of a few historical milestones that reveal the decisive role played by the FDA in the use of PROs when reviewing new treatments tested in clinical trials. These descriptions are followed by a formal definition of PROs that has now been adopted by most of the parties involved. The review continues with a focus on the different categories of PROs developed over the last two decades, well beyond the framework of clinical trials alone. Finally, it addresses recent debates on the capacity of PROs to collect and measure patient experiences, the methodological issues involved in the design of these tools, and in particular, the participation of patient organizations in the construction of PROs that better reflect the specific concerns of the people affected.