Instead of relying on prescription medications with numerous dangerous side effects, what if you could opt for a safer, natural alternative to address your health concerns? Medicinal plants for therapeutic purposes have been used for many years. The antimicrobial activity of essential oils and their major constituents has been widely documented by several works, however, in a fragmented way. Based on this premise, this book is designed to provide an overview of current knowledge about the antimicrobial properties of essential oils and their mechanisms of action, either alone or in combination, as a possible tool for obtaining new antibiotics.