"This Boy" is a song by The Beatles. The song was first released in November 1963 as the B-side of the UK Parlophone single "I Want to Hold Your Hand." The Beatles performed it on 16 February 1964 for their second Ed Sullivan Show appearance in the USA.
This is such a great live version! There's just something about the sound of those three voices, harmonizing together ("Because," for example). And I think Ringo is sunburned from the time they spent in Miami Beach:
An instrumental version of "This Boy", orchestrated by George Martin, is used as the background musical theme when Ringo does his "walkabout" in the film A Hard Day's Night. The piece, under the title, "Ringo's Theme (This Boy)" is included on the American A Hard Day's Night soundtrack album.
At the 2001 John Lennon "Come Together" concert in New York City, Rufus Wainwright performed this song with John's son Sean Lennon and actor/musician Robert Schwartzman:
Random image found whilst researching this topic (Paul and some bird on the A Hard Day's Night set):