The Karate Kid is a 1984 coming-of-age film directed by John G. Avildsen and written by Robert Mark Kamen, starring Ralph Macchio, Pat Morita and Elisabeth Shue. It is a martial arts film, and an underdog story in the mold of a previous success, Avildsen's 1976 film Rocky. It was a commercial success upon release, and garnered favorable critical acclaim, earning Pat Morita an Academy Award nomination for Best Supporting Actor.

Daniel LaRusso (Ralph Macchio) moves with his mother (Randee Heller) from Newark, New Jersey to Reseda, a neighborhood in the San Fernando Valley region of Los Angeles, California. Their apartment's handyman is an eccentric but kindly and humble Okinawan immigrant named Mr. Miyagi (Pat Morita).

Daniel befriends Ali Mills (Elisabeth Shue), a pretty high school cheerleader, at the same time angering her arrogant ex-boyfriend, Johnny Lawrence (William Zabka). Johnny is the best student at the Cobra Kai dojo, where he is taught an unethical, vicious form of martial arts. Daniel knows a little karate from books and a few classes at the YMCA, but Johnny easily defeats him in their first encounter. Thereafter, Johnny and his gang of Cobra Kai students torment Daniel at every opportunity.

When Miyagi witnesses the gang giving Daniel a particularly savage beating, he intervenes and single-handedly defeats all five young men with ease. Awed, Daniel asks Miyagi to be his teacher. Miyagi refuses, but agrees to go with Daniel to the Cobra Kai dojo in order to resolve the conflict. They confront the sensei, John Kreese (Martin Kove), an ex-Special Forces Vietnam Veteran who sneers at the concepts of mercy and restraint. Kreese and Miyagi agree to a match between Johnny and Daniel in two months' time at the "All Valley Karate Tournament," where the Cobra Kai students can fight Daniel on equal terms. Miyagi also requests that the bullying stop while Daniel trains. Kreese orders his students to leave Daniel alone, but under the condition that if Daniel does not show up for the tournament, the harassment will resume and Miyagi himself will also become a target.

Miyagi becomes Daniel's teacher and, slowly, a surrogate father figure. He begins Daniel's training by having him perform laborious chores such as waxing cars, sanding a wooden floor, refinishing a fence, and painting Miyagi's house. Each chore is accompanied with a specific movement, such as clockwise/counter-clockwise hand motions. Daniel eventually feels frustrated, believing he has learned nothing of karate. When he expresses his frustration, Miyagi reveals that Daniel has been learning defensive blocks through muscle memory learned by performing the chores.

As Daniel's training continues more overtly, his bond with Miyagi becomes closer. He learns that Miyagi lost his wife and son in childbirth at Manzanar internment camp while he was serving overseas with the United States Army during World War II. The loss of his family and Daniel's loss of his father further strengthens the father-son surrogacy. Daniel also discovers that the outwardly peaceful and serene Miyagi was a recipient of the Medal of Honor for heroism against German forces in Europe. Through the teaching, Daniel learns not only karate but also important life lessons such as the importance of balance, reflected by the belief that martial arts training is as much about training the spirit as the body. Daniel applies the life lessons that Miyagi has taught him to strengthen his relationship with Ali.

At the tournament, Daniel surprises everyone by reaching the semi-finals. Johnny advances to the finals, scoring three unanswered points against a highly skilled opponent. Kreese instructs Bobby Brown, one of his more compassionate students and the least vicious of Daniel's tormentors, to disable Daniel with an illegal attack to the knee. Bobby reluctantly does so, severely injuring Daniel and getting disqualified in the process. As Daniel writhes in pain on the ground, Bobby profusely apologizes before he is pulled away. Daniel is taken to the locker room and checked out, with the physician determining that he cannot continue. Although Miyagi assures him he has already proven himself, Daniel believes that if he does not continue, his tormentors will have gotten the best of him. He persuades Miyagi to use a pain suppression technique to allow him to finish the tournament. As Johnny is about to be declared the winner by default, Daniel hobbles into the ring. The Championship match is a seasaw battle, as neither Johnny nor Daniel are able to break through either one's defenses. At one point Daniel is knocked to the ground but takes Johnny down with him and delivers a blow to the back of the head, giving Johnny a nose bleed. The match is paused for Johnny to be looked at by Kreese.

Kreese directs Johnny to repeat unethical moves to achieve victory, such as foot sweeps to Daniel's injured leg, and rabbit punches. Johnny looks horrified at the order but reluctantly agrees after Kreese's intimidation. Despite the moves, Daniel gets up each time. At last, Daniel and Johnny are tied, with the next point deciding victory. Daniel, barely able to stand, assumes the "Crane" stance, a technique he observed Miyagi performing on the beach during his training. The referee signals to begin, and Johnny lunges in. Daniel jumps and delivers a front kick to Johnny's chin, winning the tournament. Johnny, having gained newfound respect for his adversary, takes Daniel's trophy from the Master of Ceremonies and presents it to Daniel himself, sincerely proclaiming "You're all right, LaRusso! Good match!" Miyagi looks on proudly as Daniel celebrates his victory.