The term "high E" typically refers to the highest string on a standard guitar, known as the high E string. It is tuned to the note E4, which is two octaves above middle C. This string is crucial for playing melodies and high-pitched notes in various music genres. In addition to its role in guitar playing, "high E" can also refer to the E note in music theory, which is part of the musical scale. It is often used in compositions and can be found in various instruments, including the piano and violin.