A piano chord chart is often used in pop and jazz music. It provides the harmonic progressions over which the pianist can improvise as compared to a lead sheet that provides the melody with chord symbols written above the staff.
Chord charts and lead sheets are used extensively.
Compared to classical notation where every note the composer puts down on the music paper is to be played, the jazz musician who plays with others in a band learns to create an improvisation on the spot, staying within the parameters of the meter(see the rhythm and meter page) and the chord progression that he or she believes fits in well with the other musicians' music at that moment.
An improvisation is created by ear with knowledge of a series of harmonic progressions in the music. Chord progressions are learned by listening to the melodic line while thinking of possible harmonies that make the piece come alive. The chord chart presents these progressions over which the pianist can improvise.
Have you ever listened to a jazz band? If you cannot get to a live performance here is one on YouTube.
You may even become inspired to try an improvisation on your own keyboard.
Want to learn the tools you need to do this? I am here to help you find your way in your new world of improvisation. Go to my "Comments" page if you have any questions. I will answer you soon after I receive your message.
Here is an example of a chord progression. The capital letters represent major chords and the lower case letters represents minor chords.
C F C a e F G7 C
To learn how to form and play chords on the piano/keyboard go to the page on "Harmony". Then give it a try! This may be another "I can do it" moment for you.