The sus4, or "suspended fourth," chord is an interesting harmonic build that offers a musical twist to the regular major or minor chord sound. In a sus4 chord, the third degree of the scale is "suspended" and replaced with the fourth degree, creating a characteristic open, melodic tension before resolving to a major chord. It often feels like it's somewhere in between harmonies, providing a satisfying sense of anticipation or draw towards the resolving chord. A common example is Gsus4, where the notes would be G, C, and D. It is frequently used in rock, pop, and folk music for its uplifting, yet resolving nature. When playing a sus4 on guitar, consider the context it adds to your progression as it can powerfully shift a song's emotional trajectory.