In baseball, a complete game (denoted by CG) is the act of a pitcher pitching an entire game without the benefit of a relief pitcher. The frequency of complete games has evolved since the early days of baseball. The complete game was essentially an expectation in the early 20th century and pitchers completed almost all of the games they started. In modern baseball, the feat is much more rare and no pitcher has reached 30 complete games in a season since 1975; in the 21st century, a pitcher has thrown 10 or more complete games in a season only twice.