Yogurt or yoghurt (US /ˈjoʊɡərt/ or UK /ˈjɒɡət/; other spellings listed below) is a dairy product produced by bacterial fermentation of milk. The bacteria used to make yogurt are known as "yogurt cultures". Fermentation of lactose by these bacteria produces lactic acid, which acts on milk protein to give yogurt its texture and its characteristic tang.

Worldwide, cow's milk is most commonly used to make yogurt, but milk from water buffalo, goats, ewes, mares, camels, and yaks is also used in various parts of the world.

Dairy yogurt is produced using a culture of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus bacteria. In addition, other lactobacilli and bifidobacteria are also sometimes added during or after culturing yogurt.

The milk is first heated to about 80 °C (176 °F) to kill any undesirable bacteria and to denature the milk proteins so that they set together rather than form curds. The milk is then cooled to about 45 °C (112 °F). The bacteria culture is added, and the temperature is maintained for 4 to 7 hours to allow fermentation.

John Ward or Birdy (c. 1553 – 1622), also known as Jack Ward and under his Muslim name Yusuf Reis, was a notorious English pirate around the turn of the 17th century who later became a Barbary Corsair operating out of Tunis during the early 17th century.

Little is known about Ward's early life. What little is known comes from a pamphlet purportedly written by someone who sailed with him during his pirate days. That said, Ward seems to have been born about 1553 probably in Faversham, Kent, in southeast England. Like many born in coastal areas, he spent his youth and early adult years working in the fisheries. Then, after the failed invasion of England by the Spanish Armada in 1588, he found work as a privateer, plundering Spanish ships with a license from Queen Elizabeth I of England. When James I of England assumed the throne in 1603, he ended the war with Spain and in effect put the privateers out of business. However, many of them refused to give up their livelihood and simply continued to plunder. Those who did were considered pirates because they no longer had valid licenses – called letters of marque – issued by the state. Ward appears not to have turned immediately to piracy but instead once again become a fisherman, working out of Plymouth. He was on the run from the church when he converted to Islam in the late 16th Century. His entire crew also converted to Islam with him.