What did you do today has higher complexity than the average song in terms Melodic Complexity and Chord-Melody Tension.
What did you do today is written in the key of E♭ Major. According to the Theorytab database, it is the 7th most popular key among Major keys and the 11st most popular among all keys. Major keys, along with minor keys, are a common choice for popular songs. The three most important chords, built off the 1st, 4th and 5th scale degrees are all major chords (E♭ Major, A♭ Major, and B♭ Major). See the E♭ Major Cheat Sheet for popular chords, chord progressions, downloadable midi files and more!