I V vi IV I’ve always loved Red Hot Chili Peppers, and of course their Under the Bridge song, so as a songwriter I took some time to evaluate it. Turns out to be the same chords and chord progression as zillions of other awesome songs with that progression and zillions of more that take the same 4 chords and switch it up a bit. There’s a wikipedia page about that (of course there is: https://en.wikipedia.org/wiki/List_of_songs_containing_the_I%E2%80%93V%E2%80%93vi%E2%80%93IV_progression )
However, the Chili Peppers do add a few extra surprises…a couple extra bars after the chorus to say “ya ya ya”. I’m not sure why that works but it obviously does. And the guitar intro that uses the notes in E, is beautiful. I also like how the sound is crisp and builds to the chorus then holds you there. Always one of my favorites.
I’ve used this chord progression myself a lot…probably the most obvious song is my “I Need a Song” song, where I used this chord progression sort of ironically. When I play live and I forget what to do next…go with what works. I V vi IV. It works. It sounds good.