Also known as "fetura
." Also spelled "caesura
." Most commonly spelled "railroad tracks
The cesura (an Italian term) is an element of musical notation. It can appear anywhere in a measure (except before the first note), but most commonly appears between the last note and the subsequent bar line.
The cesura indicates a significant pause in the flow of the music. The exact length, much like that of a fermata, is up to the discretion of the conductor. Occasionally, the conductor might keep directing through the cesura, with only a rallentando to mark its presence. Usually, though, the conductor comes to a full stop, and the musicians are (hopefully) silent for a moment, until directed to continue.
Particularly devious conductors have been known to exaggerate the length of a cesura in an attempt to convince the audience that the piece has concluded. Sometimes, the audience is fooled even without an exaggerated cesura. The musicians can then silently snicker at the poor audience members who applaud. The key to avoid being fooled is to watch the conductor's arms; don't clap until he or she lowers his or her arms. (That trick works to keep yourself from applauding between movements as well.)
The cesura is most commonly known as "railroad tracks." This is due to its appearance in printed notation. It consists of two parallel slanted lines. They touch the fourth line of the staff, cross the fifth (top) line, and extend one note-head's height above the staff. The slant is up and to the right. The cesura itself looks like a pair of rails, with the fourth and fifth lines of the staff representing railroad ties, thus producing the common nickname.