Czerny's 40 Daily Exercises (Op. 337) is a collection of studies for piano to help improve student's technique and performance abilities. Czerny's own instructions above the studies read: 'Each repetition should be played 20 times without interruption, ' or other numbers of repetitions. 'Daily Exercises' does not mean that all 40 studies are to be played every day, but the composer recommends that about one hour be devoted to studying part of them every day, requiring about three or four days to get through all 40 of them.