MSD Manuals is an online medical reference source that provides consumers, patients, and healthcare professionals with detailed information about diseases, symptoms, medical procedures, medications, and more. Formerly known as The Merck Manuals, this website offers access to professional-level knowledge written and reviewed by medical experts from various fields. Visitors can browse information by medical specialty, system, or symptom, and can also utilize the tools and resources of MSD Manual's clinical calculators, images and videos, and patient handouts. MSD Manuals' content is updated frequently to reflect the latest advancements in medical science and practice.