In music, the mode played by starting on E and using only the white keys of a piano is the Phrygian mode.
Those notes are E, F, G, A, B, C, and D. The crucial feature is the minor second between the tonic E and the next note F. That flattened second degree gives Phrygian its distinctive tense, often dark or exotic color. In interval terms, its scale pattern is semitone–whole tone–whole tone–whole tone–semitone–whole tone–whole tone.
Phrygian is the third mode of the diatonic major scale: E Phrygian uses the same pitch collection as C major, but E functions as the tonal center. This is why simply listing the notes is not enough; the starting and resting note determine the mode.
The common mix-up is to identify the parent key rather than the mode. Starting on D with white keys gives Dorian, F gives Lydian, and G gives Mixolydian. The mode’s name follows the tonal center, not merely the set of available piano keys.