In terms of chords and melody, Hello Again is more complex than the typical song, having above average scores in Chord Complexity, Melodic Complexity, Chord Progression Novelty and Chord-Bass Melody.
Hello Again is written in the key of F Major. According to the Theorytab database, it is the 6th most popular key among Major keys and the 6th 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 (F Major, B♭ Major, and C Major). See the F Major Cheat Sheet for popular chords, chord progressions, downloadable midi files and more!