The sheet music for popular and standard song repertoire has, for many years, been laid out with a vocal line and piano accompaniment (which sometimes reflects the vocal line), with graphic symbols for guitar, ukulele or piano chords above the vocal line.
Online song versions with the harmony are shown in graphical form above a vocal line, in a similar fashion to the traditional music sheets, but with the chords shown as text symbols – Gma or Gmaj for G major, Fmi or Fmin for F minor, etc. We shall refer to these as piano chords, or e-chords.
In popular music, as well as in jazz, flexibility and freedom in accompaniment styles is expected, and often encouraged. The notation of piano chords in this symbolic manner leaves the opportunity for the player to customise his or her own interpretation of the accompaniment with different and unique inversions and voicings, or to use the piano chords as a basis for introductions, improvisations, solos and the like.
This method of symbolic notation of harmony also benefits from not being instrument-specific – whilst the piano chords can be read by a pianist, they can also be of use to any other player of a chordal instrument – guitar, for instance. As long as the guitarist knows his or her ‘guitar chords’ in most keys, this method of notation will suffice, and indeed, most guitarists of the modern era will be more comfortable with this than standard musical staff notation.
Piano chords or e-chords found online mainly feature standard song repertoire and popular music, and usually have piano chords above or below a lyric line, with the duration of each chord denoted roughly by the position of the symbol in relation to the lyric, as opposed to being shown with a note value – half note, eighth note, etc. They’re usually accompanied by a chordal ‘dictionary’ that gives guidance to the notes of piano chords in various inversions and voicings, but these, as their name would suggest, are reference pages rather than music content pages.