Short answers, pulled from the story.
The Merchant of Venice is believed to have been written between 1596 and 1598. The playwright Francis Meres mentioned it in 1598, confirming it was already performed by that date. A reference within the play to the Spanish ship St. Andrew, captured at Cadiz in 1596, suggests composition most likely in the 1596-97 period.
The pound of flesh is the penalty clause in a loan agreement between Shylock and Antonio. Shylock agrees to lend 3,000 ducats to Bassanio with Antonio as guarantor, on the condition that if Antonio defaults, Shylock may cut exactly one pound of flesh from Antonio's body. Portia defeats this claim in court by pointing out that the bond permits flesh but not blood.
Scholars and critics disagree. Harold Bloom wrote in 1998 that the play is "a profoundly anti-semitic work." Others, including Stephen Greenblatt, argue that Shylock is given more compelling theatrical life than any other character, and that his "Hath not a Jew eyes?" speech makes a powerful case for shared humanity. The Nazis used the play for propaganda after Kristallnacht in 1938, though they feared Shylock's speeches would generate too much audience sympathy.
Edmund Kean established the tradition of playing Shylock sympathetically in the first half of the 19th century. Henry Irving's aristocratic portrayal, first seen at the Lyceum in 1879 with Ellen Terry as Portia, was called the summit of his career. Jacob Adler performed the role in Yiddish on Broadway in the early 20th century, and Al Pacino played Shylock in the 2004 film directed by Michael Radford.
The central plot elements appear in the 14th-century Italian tale Il Pecorone by Giovanni Fiorentino, published in Milan in 1558, which includes the deadly bond, the casket test, and the disguised lawyer demanding a betrothal ring. The trial scene has parallels in The Orator by Alexandre Sylvane, published in English translation in 1596. The three-casket story derives from Gesta Romanorum, a collection compiled at the end of the 13th century.
Adaptations span more than a century. In 1914, Lois Weber directed a silent film and became the first woman to direct a full-length feature film in America. A 1973 British television production starred Laurence Olivier as Shylock and Joan Plowright as Portia. The 2004 film directed by Michael Radford, with Al Pacino as Shylock and Jeremy Irons as Antonio, was the first major big-screen adaptation of the play.