Informed consent is a crucial communication process between doctors and patients for obtaining patients' approval before initiating medical treatment. It is derived from the legal principles of medical contracts and requires doctors to explain the treatment process to patients. Surgeons should be aware of informed consent not only to avoid unnecessary litigation risks but also to provide patients with the right to self-determination. The aim of the study is to help surgeons in Korea understand the legal doctrine on informed consent for practical application. This article reviews the legal doctrine of IC according to 4W1H-why, who, what, when, and how-with judicial cases to communicate effectively with patients in clinical settings. Regardless of seniority or rank, doctors may provide competent patients with information to protect their rights to self-determination. Informed consent should be advanced for patients to consider, discuss with significant others, and determine whether or not to undergo medical treatment. At that stage, patients need to be informed of the necessity, risks, and so on. The most common method of informed consent is an oral explanation utilizing certain forms for documentation. However, the informed consent of patients can be exempted on certain occasions. Optimal informed consent, when implemented, leads to patient-centered care, which significantly improves patient satisfaction and outcomes. Ultimately, it not only protects doctors from litigation risks but also upholds patients' autonomy.