Every individual visiting the emergency department may carry undiagnosed infectious diseases. This situation increases the risk of transmission to other patients in the waiting area. Patients exposed to chemical or radiological agents may also pose environmental risks. For this reason, it is critical to implement effective isolation measures at every stage, starting from the triage area where the patient is first evaluated. In some cases, more complex and detailed isolation strategies beyond standard measures may be required. Customized measures should be implemented according to each patient’s specific condition and needs. In this book, together with our experienced authors, we aim to cover the isolation scenarios we may encounter in emergency departments, from simple to complex. Our book will serve as a practical guide to the various isolation needs that emergency department personnel may encounter. By adopting the principle of “safety first,” our goal is to ensure that healthcare personnel protect themselves while delivering safe and effective care to their patients.