Tiffany & Co. (colloquially known as Tiffany's) is an American luxury jewelry and specialty design house headquartered on Fifth Avenue in Manhattan. Tiffany is known for its luxury goods, particularly its sterling silver and diamond jewelry. These goods are sold at Tiffany stores, online, and through corporate merchandising. Its name and branding are licensed to Coty for fragrances and to Luxottica for eyewear.

Tiffany & Co. was founded in 1837 by the jeweler Charles Lewis Tiffany and became famous in the early 20th century under the artistic direction of his son Louis Comfort Tiffany. In 2018, net sales totaled US$4.44 billion. As of 2023^[update], Tiffany operated over 300 stores globally, in many countries including the United States, Japan, and Canada, as well as Europe, Latin America, and the collective Asia-Pacific region, and is exploring opportunities in Africa. The company's product line features fine jewelry, sterling silver, watches, porcelain, crystal, stationery, haute couture fragrance and personal accessories, and leather goods.

On January 7, 2021, French conglomerate LVMH Moët Hennessy Louis Vuitton acquired a majority stake in Tiffany & Co. for US$15.8 billion and delisted Tiffany's stock from the New York Stock Exchange. It remains headquartered in New York City.

Tiffany & Co. was founded in 1837 by Charles Lewis Tiffany and John B. Young, in New York City, as a "stationery and fancy goods emporium", with the help of Charles Tiffany's father, who financed the store for only $1,000 with profits from a cotton mill. The store initially sold a wide variety of stationery items and, as of 1837, operated as "Tiffany, Young and Ellis" at 259 Broadway in Lower Manhattan. The name was shortened to Tiffany & Company in 1853, when Charles Tiffany took control and established the firm's emphasis on jewelry. The company has since opened stores in major cities worldwide. Unlike other stores at the time in the 1830s, Tiffany clearly marked the prices on its goods to forestall any haggling over prices. In addition, against the social norm at the time, Tiffany only accepted cash payments, and did not allow purchases on credit. Such practices (fixed prices for ready money) had first been introduced in 1750 by Palmer's of London Bridge.

The first Tiffany mail order catalog, known as the "Blue Book", was published in 1845 in the United States (U.S.), and publishing of the catalog continues in the 21st century. In 1862, Tiffany supplied the Union Army with swords (Model 1840 Cavalry Saber), flags and surgical implements. In 1867, Tiffany was the first U.S. firm to win an award for excellence in silverware at the Exposition Universelle in Paris. In 1868, Tiffany was incorporated.

In 1870, the company built a new store building at 15 Union Square West, Manhattan, which was designed by John Kellum and cost US$500,000. It was described by The New York Times as a "palace of jewels." Tiffany stayed at this site until 1906.

In 1877, an insignia that would become the New York Yankees "NY" logo was struck on a police medal of honor by Tiffany; the Yankees adopted the logo in 1909. In 1878, Tiffany won the gold medal for jewelry and a grand prize for silverware at the Paris Exposition. In 1879, Tiffany purchased one of the world's largest yellow diamonds which became known as the Tiffany Diamond. The Tiffany Diamond has only been worn by four people, one of whom was Audrey Hepburn for the promotion of Breakfast at Tiffany's. In 1887, Tiffany bought a number of pieces at the auction of part of the French Crown Jewels, which attracted publicity and further solidified the Tiffany brand's association with high-quality diamonds. The company revised the Great Seal of the United States in 1885.

In 1902, after the death of Charles Lewis Tiffany, his son, Louis Comfort Tiffany, became the company's first official design director.