Short answers, pulled from the story.
Romeo and Juliet is based primarily on Arthur Brooke's 1562 English verse translation The Tragical History of Romeus and Juliet, which itself derived from Matteo Bandello's 1554 Italian novella. The earliest known version of the story was published by Masuccio Salernitano in 1476. Luigi da Porto gave the story its Veronese setting and the names Romeo and Juliet in a work written in 1524 and published in 1531.
Scholars believe Romeo and Juliet was written between 1591 and 1595. A reference in the text to an earthquake eleven years earlier may point to the Dover Straits earthquake of 1580, placing that line in 1591. The play's stylistic similarities with A Midsummer Night's Dream support a date of around 1594-95, and the first printed edition appeared in early 1597, making 1596 the latest possible date of composition.
The Lord Chamberlain's Men were the first company to perform Romeo and Juliet, likely at The Theatre. Richard Burbage was probably the first Romeo, as the company's chief tragedian, and Master Robert Goffe, a boy actor, likely played Juliet. A shortened version was performed in Nördlingen, Germany in 1604, making it one of the first Shakespeare plays staged outside England.
Q1, printed in 1597 by John Danter, is considered a corrupt text, likely reconstructed from actors' memories, and is about 800 lines shorter than Q2. Q2, printed in 1599 by Thomas Creede, is believed to have been set from Shakespeare's own working draft and is the basis for all subsequent editions, including the First Folio of 1623 and all modern versions.
Shakespeare's original text did not include a balcony; it only indicates that Juliet appears at a window. The word balcone was not known in English until two years after Shakespeare's death. The balcony was introduced into the theatrical tradition by David Garrick's 18th-century adaptation, following its appearance in Thomas Otway's 1679 play The History and Fall of Caius Marius.
West Side Story, with music by Leonard Bernstein and lyrics by Stephen Sondheim, is the most famous musical theatre adaptation; it debuted on Broadway in 1957 and was filmed in 1961 and 2021. Prokofiev's ballet score, originally commissioned by the Kirov Ballet in the 20th century, has attained an immense reputation and has been choreographed by John Cranko in 1962 and Kenneth MacMillan in 1965. At least 24 operas have been based on the play, the best known being Gounod's 1867 Roméo et Juliette.