Chord chart
A chord chart (or chart) is a form of musical notation that describes the basic harmonic and rhythmic information for a song or tune. It is the most common form of notation used by professional session musicians playing jazz or popular music. It is intended primarily for a rhythm section (usually consisting of piano, guitar, drums and bass). In these genres the musicians are expected to be able to improvise the individual notes used for the chords (the "voicing") and the appropriate ornamentation, counter melody or bassline.
In some chord charts, the harmony is given as a series of chord symbols above a traditional musical staff. The rhythmic information can be very specific and written using a form of traditional notation, sometimes called rhythmic notation, or it can be completely unspecified using slash notation, allowing the musician to fill the bar with chords or fills any way they see fit (called comping). In Nashville notation the key is left unspecified on the chart by substituting numbers for chord names. This facilitates on-the-spot key changes to songs. Chord charts may also include explicit parts written in modern music notation (such as a musical riff that the song is dependent on for character), lyrics or lyric fragments, and various other information to help the musician compose and play their part.
Rhythmic notation[edit]
Rhythmic notation specifies the exact rhythm in which to play or comp the indicated chords. The chords are written above the staff and the rhythm is indicated in the traditional manner, though pitch is unspecified through the use of slashes placed on the center line instead of notes. This is contrasted with the less specific slash notation.[1]
Grid notation[edit]
In some European countries (France particularly), pop and jazz musicians often use so-called "chord grids" that show in a graphical way the chord progression. To illustrate, below is an example of two-part tunes, each eight bars long. Each square stands for a bar, while the "•/•”symbol means to stay on the same chord as the previous bar. The song structure can then be written down as a succession of the different parts. For example A-A-B-A, that would mean to play twice the "A" part, once the "B" part, and then again once the "A" part.
Squares can also be separated diagonally for bars having two chords, as in the example below: