Short answers, pulled from the story.
Paul McCartney wrote "Hey Jude" and it was credited to the Lennon-McCartney partnership. McCartney composed the song while driving to Weybridge in June 1968 to visit Julian Lennon, John Lennon's five-year-old son, after Lennon had left his wife Cynthia for Yoko Ono.
McCartney originally titled the song "Hey Jules" because it was written to comfort Julian Lennon during his parents' separation. McCartney changed the name to "Jude" because, as he put it, he thought that sounded a bit better.
"Hey Jude" held the number-one position on the Billboard Hot 100 for nine weeks after reaching the top on the 28th of September 1968. That nine-week run tied the all-time record for the longest run at the top of the US charts in 1968, a record that stood for nine years.
The master track was recorded at Trident Studios in central London on the 31st of July 1968. "Hey Jude" was the first Beatles song recorded on eight-track equipment; EMI Studios, where the group had recorded their rehearsal takes, was still limited to four tracks.
By 1999, "Hey Jude" had sold an estimated eight million copies worldwide and was certified 4x platinum by the RIAA, representing four million units shipped in the United States. As of December 2018, it was the 54th-best-selling single of all time in the UK.
"Hey Jude" was the Beatles' first release on their Apple Records label and one of four singles issued simultaneously to mark the label's public launch in August 1968. It was the label's most successful debut single, contrasting with the recent closure of Apple Boutique, the band's short-lived retail venture.