"Revolution" was written by John Lennon during a time when he was struggling with this politics and the way he related to the world. It was right in the midst of the Vietnam War, and though Lennon had yet to become anti-establishment, he was definitely anti-war. "Revolution" was the manifestation of that, and the song first became an anthem of rebellion before moving on to be an iconic classic.
It's also been covered a lot on stage and online, but this particular cover has something special: It's performed by a father-daughter team, and their performance is perfect.
These two guys played a child's guitar at Walmart. You have to hear it.