"The Greatest of All Time," Muhammad Ali, celebrated his 68th birthday on Sunday.
Although it has been 28 years since his last fight, Ali remains one of the most beloved and recognizable figures in boxing history.
This slideshow is a simple tribute to the most charismatic boxer the world has ever known.
Muhammad Ali was born Cassius Marcellus Clay on Jan. 17, 1942 in Louisville, Kentucky. He began his boxing career at the age of 12.
He won the national Golden Gloves championship in the middleweight division in 1959 and again in 1960.
Clay then went on to win the the AAU national light heavyweight title before competing in the 1960 Summer Olympics.
Cassius Clay takes his place on the stand after winning a gold medal as a light heavyweight in the 1960 Summer Olympics in Rome.
Clay completed his amateur career with a record of 100 wins and five losses.
Immediately following his Olympic victory, Clay began his professional career.
This photograph shows him competing in his first professional fight against Tunney Hunsaker on October 29, 1960.
He won the six round contest by unanimous decision.
On Feb. 25, 1964, Clay challenged Heavyweight Champion, Sonny Liston.
Clay had difficulty with his vision during the fight due to an unknown substance that came from Liston's gloves.
Some believe that the substance was simply an ointment that had been used to treat Liston's cut. Others think that the chemical was purposely applied to Liston's gloves.
Angelo Dundee said that he rubbed Clay's eyes, and then his own. Dundee said, "...it burned".
Clay managed to avoid Liston's punches by employing his superb footwork and agility—allowing time for his tear ducts to clear his eyes.
Liston refused to answer the bell for round seven, claiming an injured shoulder.
Clay became the youngest boxer to ever win the title from an existing heavyweight champion. He was 22 years old at the time.
After his victory, Clay announced that he had converted to Islam and changed his name to Muhammad X. He later changed it to Muhammad Ali.
On May 25, 1965 Ali defended his title for the first time in a rematch with Sonny Liston.
Most of round one was fairly uneventful as Ali used every square inch of the ring, showcasing his exceptional footwork. Liston stalked Ali but was unable to land any significant shots.
Finally, Ali landed a short, choppy right that became known as the "Phantom Punch".
Liston managed to get up and referee "Jersey" Joe Walcott allowed the fight to continue for a short time before being told by the time-keeper that Liston had been down for a full 17 seconds.
The official stoppage came at the 2:12 mark of round one.
On Feb. 6, 1967, Ali faced Ernie Terrell.
Prior to the fight, during an interview with Howard Cosell, Ali became furious at Terrell due to his refusal to call him by his Muslim name.
Ali said: "My name is Muhammad Ali, and you will announce it right there in the center of that ring if you don't do it now."
Terrell refused, and an altercation between the two men broke out during the interview.
During the fight Ali punished Terrell for the full 15 rounds—often pausing to yell, "What's my name?!!".
Ali's antics were highly controversial. Many felt that Ali could have easily ended the fight early but simply chose to deal Terrell as much punishment as possible.
Ali's victory came by unanimous decision.
On March 8, 1971 Ali faced undefeated champion, "Smokin'"Joe Frazier. The bout was billed as "The Fight of the Century".
Ali had been stripped of the title in June of 1967 after refusing to be inducted into the army.
Ali won many of the early rounds, but Frazier was able to withstand Ali's combinations.
Frazier staggered Ali in the 11th round and knocked him to the canvas in round 15.
Frazier won by unanimous decision, dealing Ali his first professional loss.
On Jan. 28, 1974, Ali faced Frazier once again. Frazier had recently lost his WBC and WBA heavyweight titles to George Foreman.
In their second battle, Ali was victorious over Frazier by unanimous decision.
At 4:00 a.m. on Oct. 30, 1974, in Zaire, Africa, Muhammad Ali faced "Big" George Foreman—the undisputed heavyweight champion of the world.
The younger, bigger, and stronger Foreman had a record of 40-0 with 37 KOs.
Foreman was heavily favored to win the match.
Ali—who had vowed to dance circles around his more powerful yet slower opponent—came out punching and scoring in round one.
Ali soon abandoned this strategy and retreated to the ropes. He remained there for much of the fight.
Ali invited Foreman to throw everything he had to offer as he laid back on the ropes and blocked many of the powerful bombs. This strategy became known as the "Rope a Dope".
By round eight, Foreman was totally exhausted.
With only 15 seconds remaining in the round, Ali stepped off the ropes and executed a beautiful combination—punctuated with a vicious straight right that sent "Big" George Foreman to the canvas.
Muhammad Ali had accomplished what most had believed to be impossible. He beat George Foreman to regain the title of undisputed heavyweight champion of the world.
The Ali-Frazier trilogy was completed on Oct. 1, 1975 in Quezon City, Metro Manila Philippines.
The fight started long before the boxers stepped into the ring. Ali taunted and ridiculed Frazier at every opportunity during the promotions leading up to the fight.
During an interview, Ali punched a toy gorilla and made the famous statement: "It will be a killa...and a chilla...and a thrilla...when I get the gorilla in Manila."
Frazier was infuriated by the brash statements and insults.
The bout is widely recognized as one of the greatest battles in boxing history. Both fighters gave every ounce of energy they could muster.
Frazier's trainer, Eddie Futch, stopped the fight after the 14th round.
An exhausted Ali retired on a stool in the middle of the ring after the fight. He said, "Joe Frazier is the greatest boxer in the world next to me."
In February of 1978 Ali lost his title to Leon Spinks by split decision.
He regained it in their rematch in September of the same year by a unanimous decision win.
Following losses to Larry Holmes and Trevor Berbick, Muhammad Ali retired in 1981 with a record of 56-5 with 37 KOs.
In 1996, Muhammad Ali received the high honor of lighting the cauldron for the Olympic Games in Atlanta, Georgia.
The awards and honors that have been rightfully bestowed upon the man are too numerous to mention.
There would be no way to repay all that Muhammad Ali has given to the sport of boxing.
That's why he will always be "The Greatest of All Time".
"Champions aren't made in gyms. Champions are made from something they have deep inside them-a desire, a dream, a vision. They have to have last-minute stamina, they have to be a little faster, they have to have the skill and the will. But the will must be stronger than the skill."