Daf yomi, which means “page a day” or “daily page,” is the study of a double-sided page of Talmud every day, in sync with Jews all over the world who are also studying the same text.
Daf yomi was created by Rabbi Meir Shapiro in 1923 as a way to encourage wider study of the Talmud and to build unity among Jews. Imagine, he said (and I paraphrase), a Jew in Europe sails across the sea, studying the daf each day. Upon his arrival in America, he goes to a synagogue and sees that the Jews there are on the exact same page.
Since 1923, the entire 2,711-page cycle, which lasts seven-and-a-half years, has been completed 12 times. The 13th daf yomi cycle will come to an end on January 4, 2020, and the 14th cycle will begin the next day.