Lennon has inspired me personally more than any other artist I've ever been exposed to. His music got me through some difficult times growing up but showing me that there was something better in the world than the abuse I grew up with.
Lennon taught me to question authority, to think outside the spiritual box and the importance of one person standing up to injustice and saying, "No."
There will be fan tributes around the world tonight for the man who changed a generation. BBC News reports:
Fans will gather at a memorial garden in Central Park, New York, opposite the apartment block where he was shot dead.
A vigil will also be held in Liverpool at a monument dedicated to the singer where fans will light candles and sing his songs.
Lennon's widow, Yoko Ono, has urged people to remember him with "deep love and respect".
She said: "On this tragic anniversary, please join me in remembering John.
"In his short-lived life of 40 years, he has given so much to the world. The world was lucky to have known him. We still learn so much from him today."
Ono was with Lennon when he was killed by crazed fan Mark Chapman outside the Dakota building in Manhattan, where the couple lived.
Ono will lead the tributes at a charity concert she has organised in Japan called Dream Power John Lennon Super Live, which raises money for schools for deprived children all over the world.
Events will also take place across Liverpool - Lennon's home city - to remember the singer.
Charity concert Lennon Remembered - The 9 Faces of John, will feature the Liverpudlian's friends and bandmates from his first band, The Quarrymen, performing his most famous songs.
John is remembered most for his years with The Beatles. His best known solo work is probably "Imagine", but my personal favorite will always be "Mind Games".