In-ear monitors, commonly known as IEMs, are small audio devices designed to fit snugly inside the ear canal. They are often used by musicians and audio professionals to hear a mix of sounds during live performances or studio recordings. IEMs provide a more personalized listening experience by isolating external noise, allowing users to focus on the audio. IEMs come in various styles and configurations, including single-driver and multi-driver designs. They can be custom-molded to fit an individual's ear shape or come in universal sizes. Many audiophiles also use IEMs for casual listening, appreciating their sound quality and portability.