The "Csus2" chord is a suspended chord built on the root note C. It consists of the notes C, D, and G. The "sus" in its name stands for "suspended," indicating that the third note of a major chord is replaced by the second note. This gives the chord a unique, open sound that is often used in various music genres. In terms of guitar playing, the Csus2 chord can be played by placing fingers on specific frets to create the desired notes. It is commonly used in progressions to add tension and resolution, making it a popular choice among songwriters and musicians.