Tetracycline is a broad-spectrum antibiotic belonging to the tetracycline class, which also includes antibiotics such as doxycycline and minocycline. It is one of the most commonly prescribed antibiotics, used to treat a wide range of bacterial infections such as pneumonia, acne, and urinary tract infections. Tetracycline was first discovered in the 1940s and has been used extensively for over half a century. Despite newer antibiotics being introduced, tetracycline is still a vital drug in the medical field and continues to be prescribed due to its effectiveness, low cost, and availability in various formulations. In this book, we will explore the history, chemical structure, medical uses, side effects, interactions, and regulations of tetracycline.