Drop D tuning is a popular guitar tuning where the lowest string, usually the sixth string, is tuned down one whole step from E to D. This adjustment creates a deeper, richer sound and allows for easier power chords and certain chord shapes. It is commonly used in various music genres, including rock and metal. In Drop D tuning, the remaining strings (fifth to first) remain in standard tuning (A, D, G, B, E). This tuning provides guitarists with a unique way to explore different chord voicings and riffs, making it a favorite among musicians like Soundgarden and Led Zeppelin.