Bis is a Latin prefix or suffix designating the second instance of a thing, thus preceding ter. An example in recent modern usage is the ITU-T modem standard from the late 20th century, V.32bis. Bis can also refer to:
Pachelbel's Canon in D major, a piece of chamber music scored for three violins and basso continuo and originally paired with a gigue in the same key, experienced a tremendous surge in popularity during the 1970s.
The D major chord I is the D major chord, and contains the notes D, F#, and A. This tonic chord's root / starting note is the 1st note (or scale degree) of the D major scale. The roman numeral for number 1 is 'I' and is used to indicate this is the 1st triad chord in the scale.