Rheumatoid arthritis (RA), a debilitating autoimmune disease, has witnessed tremendous progress in treatment options over the past decades, particularly with the advent of biological therapies. These treatments, which target specific molecules involved in the inflammatory cascade, have revolutionized the way clinicians manage patients who have failed to respond to conventional therapies. As biologics have entered clinical practice, so have biosimilars—affordable alternatives that promise wider access while maintaining efficacy and safety. As the field of biologics continues to expand, it is essential to remain up-to-date on best practices, including screening for latent infections, managing comorbidities such as cardiovascular disease and diabetes, and ensuring patient education on biologic use. This first book in the series, titled Introduction to Biologics, is intended as a practical reference for both practicing rheumatologists and clinicians new to biologic therapy. It addresses the scientific, clinical, and regulatory considerations surrounding biologics and biosimilars, with a particular focus on their application in RA. By compiling the latest insights and research, I hope this book will empower healthcare professionals to make informed decisions regarding biologic therapy and ensure the best possible outcomes for patients with RA