Essential oils are complex mixtures of volatile compounds obtained from plants where they play aromatic, communicative and defensive roles. They have been used for centuries in medicine, agriculture and industry due to their broad spectrum of biological activity. They exhibit antimicrobial, antiviral, anti-inflammatory, antioxidant and smooth muscle relaxant properties. Due to their lipophilicity and small molecular size, essential oil components easily penetrate biological membranes and exert therapeutic effects. Currently, research is underway on the use of essential oils for the treatment of viral infections, cancer prevention and inflammatory diseases. These agents may provide a valuable alternative to conventional therapies due to their natural origin and high tolerability. However, ensuring the appropriate quality and standardization of preparations is crucial to guarantee their efficacy and safe use. This paper provides an overview of the properties of essential oils, the methods used to obtain them, their composition, and their medical and therapeutic applications.