The high E string is the thinnest string on a standard guitar, typically tuned to the note E in the second octave. It is located at the bottom of the guitar when held in playing position and is essential for playing melodies and high-pitched notes. In standard tuning, the high E string is the first string, and it plays a crucial role in various musical styles. It is often used for solos, riffs, and chords, making it a vital component for both beginners and experienced players.