This may seem like a basic question, but...

[Dioptase]

Sometimes looking at chord charts, mostly rock songs, I see chords listed such as
D/A or E/A

What does this mean? Does one chord move swiftly to another, or is a note added to a chord?

Thanks for your help!

[Jon Hall]

I've always understood it to mean a chord with a specific bass note. E/A = E maj with an A bass note D/A = D maj with an A bass note.

The simplest bass line to a chord progression would be the root note of each chord except when a bass note is specified.

[Nathan Sanders]

Jon, you are correct. The bottom note is the bass note. So, D/A = D maj with an A bass note, for example.

[Dioptase]

Thanks for the help, much obliged.
Micah