People are confused about the hook. Even people in the music business, people who should know better, are confused about the hook. I have often heard them remark that the chorus of a song is the hook. Well, no, it isn't. The hook may be in the chorus, or it may be in the verses, or it may be in both. Like it is in "She Loves You," by those very talented Hookmeisters, the Beatles.
The song starts with the chorus, and the hook shows up right away. "She loves you, yeah, yeah, yeah . . ." The "yeah, yeah, yeah" part is the hook, but really the hook is the descending three note figure in a minor key that carries the "yeah, yeah, yeah."
The same hook shows up in the verses without the "yeah, yeah, yeah" part. "She said she loves you, and you know that can't be bad, (brang, brang, brang)." The "brang, brang, brang" part is the same three note descending figure played in minor chords on the guitar. It's a very good song, with a hook so strong that it showed up in juke boxes all over the world, including in many countries where it was the first English language song that anyone had ever heard. You can't argue with success like that. That hook worked.
The Beatles clearly understood the power of the hook. Their songs are full of hooks, usually multiple hooks. There are two more hooks in "She Loves You." One shows up three times: after the first chorus; after the first verse; and after the second chorus. It's there to highlight the space between chorus and verse, to draw attention to the structure of the song. The main purpose of hooks is to make the song memorable, but this hook is there to avoid dead spots. There's a third hook that shows up only in the ending, which is what, a modified verse? "With a love like that, you know you should be glad," with a "bum, bum, bum, bum," after it twice. Then the big finish!
If you are running through a song in your head, and there are little, repeating musical features that are important to include in your memory of the song, those are probably hooks. Songs without hooks are poor dead things; they just lay there like dead fish. Thank God for hooks.