George Harrison wrote this. It was inspired by his wife, Pattie.
A verse was edited out of album version, cutting time from 8 minutes to 6. The full version appears in film Yellow Submarine.
This was by far the longest Beatles song until "Hey Jude" was recorded over a year later. (thanks, Adrian - Wilmington, DE)
Paul McCartney played lead guitar on this song and John Lennon supplied the guitar feedback, allowing George to be free to concentrate only on vocals during the recording of this song. (thanks, Jonathon - Clermont, FL)