The Joker is a fictional supervillain created by Bill Finger, Bob Kane, and Jerry Robinson who first appeared in the debut issue of the comic book Batman (April 25, 1940), published by DC Comics. Credit for the Joker's creation is disputed; Kane and Robinson claimed responsibility for the Joker's design, while acknowledging Finger's writing contribution. Although the Joker was planned to be killed off during his initial appearance, he was spared by editorial intervention, allowing the character to endure as the archenemy of the superhero Batman. In his comic book appearances, the Joker is portrayed as a criminal mastermind. Introduced as a psychopath with a warped, sadistic sense of humor, the character became a goofy prankster in the late 1950s in response to regulation by the Comics Code Authority, before returning to his darker roots during the early 1970s. As Batman's nemesis, the Joker has been part of the superhero's defining stories, including the murder of Jason Todd—the second Robin and Batman's ward—and the paralysis of one of Batman's allies, Barbara Gordon. The Joker has had various possible origin stories during his decades of appearances. The most common story involves him falling into a tank of chemical waste which bleaches his skin white and turns his hair green and lips bright red; the resulting disfigurement drives him insane. The antithesis of Batman in personality and appearance, the Joker is considered by critics to be his perfect adversary. The Joker possesses no superhuman abilities, instead using his expertise in chemical engineering to develop poisonous or lethal concoctions, and thematic weaponry, including razor-tipped playing cards, deadly joy buzzers, and acid-spraying lapel flowers. The Joker sometimes works with other Gotham City supervillains such as the Penguin and Two-Face, and groups like the Injustice Gang and Injustice League, but these relationships often collapse due to the Joker's desire for unbridled chaos. The 1990s introduced a romantic interest for the Joker in his former psychiatrist, Harley Quinn, who becomes his villainous sidekick. Although his primary obsession is Batman, the Joker has also fought other heroes including Superman and Wonder Woman. One of the most iconic characters in popular culture, the Joker has been listed among the greatest comic book villains and fictional characters ever created. The character's popularity has seen him appear on a variety of merchandise, such as clothing and collectable items, inspire real-world structures (such as theme park attractions), and be referenced in a number of media. The Joker has been adapted to serve as Batman's adversary in live-action, animated, and video game incarnations, including the 1960s Batman television series (played by Cesar Romero) and in film by Jack Nicholson in Batman (1989), Heath Ledger in The Dark Knight (2008), and Jared Leto in Suicide Squad (2016). Mark Hamill, Troy Baker, and others have provided the character's voice.

Jolly Roger is the traditional English name for the flags flown to identify a pirate ship about to attack, during the early 18th century (the later part of the Golden Age of Piracy). The flag most commonly identified as the Jolly Roger today, the skull and crossbones symbol on a black flag, was used during the 1710s by a number of pirate captains including Black Sam Bellamy, Edward England, and John Taylor, and it went on to become the most commonly used pirate flag during the 1720s.

Jon Olsson is a professional freeskier and alpine ski racer, born in Mora, Sweden (17 August 1982). Olsson started his career as a ski racer but at age 16 he switched his race skis for twin tips and quit ski racing. Eight years later, after a 50 000 SEK (5826.22 USD) bet with fellow skier Jens Byggmark, Olsson started ski racing again with the goal of the bets being to make it to the Olympics in 2014. He now competes in both freestyle and ski racing. Olsson is known for his invention of several new double flips, including a D-spin 720 into a flatspin 540 (DJ flip), a switch double rodeo 1080 (hexo flip), a double flatspin 900 (kangaroo flip), and a switch cork 720 to flatspin 540 (the tornado). Olsson holds nine Winter X_Games medals (+ 2 podiums in big air). He has also won many other events including big air at Winter X-Games 08, The US Free Skiing Open in Vail, The Red Bull Big Air in Åre, Scandinavian Big Mountain Championships in Riksgränsen and the World Superpipe Championships in Whistler BC. Since Olsson's return to alpine ski racing in 2008 he has won five FIS gs ski racers, with a 10 point fis result at Coronet Peak at the New Zealand National Championships which included a field of Olympians including Ben Griffin and Olivier Jenot. Since 2005 Olsson has hosted the big air event Jon Olsson Invitational, also known as JOI. In 2007 the event was voted best big air event by freeskier magazine. From 2007 to 2010 he also hosted Jon Olsson Super Sessions (JOSS), a freeskiing film contest that takes place in Åre, Sweden. The event consisted of teams of skiers skiing for approximately two weeks with a film crew and creating a short ski film. Olsson made his debut in the Alpine Skiing World Cup in Val-d'Isère in December 2010, as part of a plan to make the Swedish alpine ski team at the 2014 Winter Olympics. Hans Olsson, a Swedish alpine skier specialising in the speed events, is Jon Olsson's brother.

Jon Snow is a fictional character in the A Song of Ice and Fire series of fantasy novels by American author George R. R. Martin, and its television adaptation Game of Thrones, in which he is portrayed by English actor Kit Harington. He is a prominent point of view character in the novels, and has been called one of the author's "finest creations" and most popular characters by The New York Times. Jon is a main character in the TV series, and his storyline in the season 5 finale generated a strong reaction among viewers. Speculation about the character's parentage has also been a popular topic of discussion among fans of both the books and the TV series. Jon is introduced in 1996's A Game of Thrones as the illegitimate son of Ned Stark, the honorable lord of Winterfell, an ancient fortress in the North of the fictional continent of Westeros. Knowing his prospects are limited by his status, Jon joins the Night's Watch, who guard the far northern borders from the wildlings who live beyond The Wall. As the rest of the Starks face grave adversity, Jon finds himself honor bound to remain with the Watch. In A Clash of Kings (1998), he joins a scouting party investigating the growing threat from the otherworldly "Others" beyond the Wall, and manages to infiltrate the wildlings. Jon learns of their plans to invade Westeros in A Storm of Swords (2000), and begins to fall in love with the fierce wildling woman Ygritte. He betrays them—and Ygritte—before they can attack, but the Night Watch's victory comes at a heavy price for Jon. Now the Lord Commander of the Watch, he appears briefly in 2005's A Feast for Crows. Jon returns as a prominent character in a A Dance with Dragons (2011), working to negotiate an alliance between the Night's Watch and the wildlings. The growing animosity he has attracted from among the Watch finally catches up with him, and he is forced to face the dire consequences. On the HBO series Game of Thrones, Jon's storyline follows the character's plot arc from the novel series, though season 6, season 7 and season 8 of the TV adaptation continue on from the events of Martin's latest published installment. Harington was nominated for a Primetime Emmy Award for Outstanding Supporting Actor in a Drama Series for the role in 2016. He was also nominated for a Saturn Award for Best Supporting Actor on Television in 2012, 2016 and 2017.

Joseph Herscher better known his YouTube pseudonym Joseph's Machines is YouTube personality, kinetic artist, specializes in making comical chain-reaction machines. He made his first machine when he was five, the Lolly Machine.

Joule heating, also known as Ohmic heating and resistive heating, is the process by which the passage of an electric current through a conductor produces heat. Joule's first law, also known as the Joule–Lenz law, states that the power of heating generated by an electrical conductor is proportional to the product of its resistance and the square of the current: P ∝ I 2 R {\displaystyle P\propto I^{2}R} Joule heating affects the whole electric conductor, unlike the Peltier effect which transfers heat from one electrical junction to another.

Journalism is the production and distribution of reports on recent events. The word journalism applies to the occupation, as well as citizen journalists using methods of gathering information and using literary techniques. Journalistic media include print, television, radio, Internet, and, in the past, newsreels. Concepts of the appropriate role for journalism vary between countries. In some nations, the news media are controlled by government intervention and are not fully independent. In others, the news media are independent of the government but instead operate as private industry motivated by profit. In addition to the varying nature of how media organizations are run and funded, countries may have differing implementations of laws handling the freedom of speech and libel cases. The advent of the Internet and smartphones has brought significant changes to the media landscape in recent years. This has created a shift in the consumption of print media channels, as people increasingly consume news through e-readers, smartphones, and other personal electronic devices, as opposed to the more traditional formats of newspapers, magazines, or television news channels. News organizations are challenged to fully monetize their digital wing, as well as improvise on the context in which they publish in print. Newspapers have seen print revenues sink at a faster pace than the rate of growth for digital revenues.

A journalist is a person who collects, writes, or distributes news or other current information to the public. A journalist's work is called journalism. A journalist can work with general issues or specialize in certain issues. However, most journalists tend to specialize, and by cooperating with other journalists, produce journals that span many topics. For example, a sports journalist covers news within the world of sports, but this journalist may be a part of a newspaper that covers many different topics.

The word joy means a feeling of great pleasure and happiness.C. S. Lewis saw clear distinction between joy, pleasure, and happiness: "I sometimes wonder whether all pleasures are not substitutes for Joy.", and "I call it Joy, which is here a technical term and must be sharply distinguished both from Happiness and Pleasure. Joy (in my sense) has indeed one characteristic, and one only, in common with them; the fact that anyone who has experienced it will want it again... I doubt whether anyone who has tasted it would ever, if both were in his power, exchange it for all the pleasures in the world. But then Joy is never in our power and Pleasure often is."The causes of joy have been ascribed to various sources. “When the mind is pure, joy follows like a shadow that never leaves.” Gautama Buddha, "[Joy is] the emotional dimension of the good life, of a life that is both going well and is being lived well."Miroslav Volf, "This is the true joy in life, the being used for a purpose recognized by yourself as a mighty one; the being thoroughly worn out before you are thrown on the scrap heap; the being a force of Nature instead of a feverish selfish little clod of ailments and grievances complaining that the world will not devote itself to making you happy." George Bernard Shaw and “Find a place inside where there's joy, and the joy will burn out the pain.” Joseph Campbell.

A joystick is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. A joystick, also known as the control column, is the principal control device in the cockpit of many civilian and military aircraft, either as a center stick or side-stick. It often has supplementary switches to control various aspects of the aircraft's flight. Joysticks are often used to control video games, and usually have one or more push-buttons whose state can also be read by the computer. A popular variation of the joystick used on modern video game consoles is the analog stick. Joysticks are also used for controlling machines such as cranes, trucks, underwater unmanned vehicles, wheelchairs, surveillance cameras, and zero turning radius lawn mowers. Miniature finger-operated joysticks have been adopted as input devices for smaller electronic equipment such as mobile phones.