Yo (/joʊ/ YOH) is a slang interjection,[1] commonly associated with North American English. It was popularized by the Italian-American community in Philadelphia, Pennsylvania, in the 1940s.[2]
Although often used as a greeting and often deployed at the beginning of a sentence, yo may also come at the end of a sentence and/or may be used to place emphasis on or to direct focus onto a particular individual, group, or issue at hand, or to gain the attention of another individual or group. It may also be used to express excitement, surprise, disbelief, enthusiasm, anger, or amazement.