John Lennon's life was tragically cut short on Dec. 8, 1980 by four bullets from an assassin's gun in New York City. In these days of instant gratification, instant fame and disposable heroes, it seems almost quaint to acknowledge someone like Lennon.

Real in an unreal world, despite the insane heights of fame he reached, he never seemed like anyone but John Lennon. Sure, that definition may have changed a bit over the years. Certainly the Lennon of 1980 was a somewhat different figure from the Lennon of 1972 or 1964, but through all his life, he was still John.

Musician, singer, songwriter, author, artist, activist: What can be said about the man that hasn't been said a million times over? From humble and troubled beginnings, Lennon would go on to change the world with his music, words, wit and his often open-wound approach to living life.

He and Paul McCartney became the most successful songwriting team of the 20th century. The two wrote songs that became standards. Other artists would over time sell more records and play to larger stadiums of fans, but no one matched the impact of the Beatles. It was a time and place never to happen again. Not bad for a bunch of kids who simply loved playing and writing rock 'n' roll songs.

Watch Coverage of John Lennon's Murder From 1980

Their constant desire to write better songs, to find new sounds and new ways of doing things, moved music (and pop culture) in directions no one at the dawn of the '60s could have ever imagined. From "She Loves You" to "Strawberry Fields Forever" in just three years? Incredible! For that matter, the Beatles' entire career was there and gone in the time it now takes many bands to release their second or third albums.

Married at a young age, he and his first wife Cynthia had one son, Julian, but due to the explosion of the Beatles, he was gone for much of Julian's childhood. In 1968, he met the woman who would become his second wife, Yoko Ono, and the two were famously inseparable. John always seemed to follow his heart both musically and personally. His solo catalog drives like a car on a bumpy road, with some incredible highlights and some highly questionable lows, yet anything but dull.

In the early '70s, John and Yoko had moved to New York City, a place he very much loved. During this era, his outspoken opposition to the Vietnam war and the Nixon administration led Nixon to attempt to silence him under the watchful eyes of the FBI, ultimately leading to the threat of deportation. Lennon dropped out of music altogether when his son Sean was born in 1975, famously playing the role of househusband for five years until the spark to make music struck again in 1980. The resulting album, Double Fantasy, was released barely a month before he was killed.

Watch Coverage of John Lennon's Murder From 1980

Lennon's music lives on today. His songs, solo and with the Beatles, are still heard everywhere. They've taken on new forms and shape-shifted their way into the hearts and minds of younger generations along the way. It would be hard to tell someone where to start on a journey through Lennon's music, but albums like Help, Revolver, the White Album, Plastic Ono Band or Imagine provide a good launch pad.

It's impossible to imagine a world anymore without Lennon or the Beatles. This would certainly be a much different place had Lennon, McCartney, George Harrison and Ringo Starr never existed. It's almost impossible to overstate their impact on the world at large, let alone the music world.

As the years have passed since Lennon was murdered in cold blood on the streets of his favorite city by a so-called fan, there's still no way to understand the insanity of the act. Yet, thankfully, the joy and excitement of Lennon and his music remain.

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