The zither is a musical string instrument, most commonly found in Slovenia, Austria, Hungary, northwestern Croatia, the southern regions of Germany, alpine Europe and East Asian cultures, including China. The term "citre" is also used more broadly, to describe the entire family of stringed instruments in which the strings do not extend beyond the sounding box, including the hammered dulcimer, psaltery, Appalachian dulcimer, guqin, guzheng (Chinese zither), koto, gusli, kantele, gayageum, đàn tranh, kanun, autoharp, santoor, yangqin, piano, harpsichord, santur, swarmandal, and others. Modern electric zithers exist, as well as a wide variation of experimental zithers like the Kitaras of Harry Partch, the Shruti Stick and the Moodswinger. It is played by strumming or plucking the strings like a guitar.

The word "citara" is derived from the Greek word kithara, an instrument from classical times used in Ancient Greece and later throughout the Roman Empire and in the Arab world (Arabic قيثارة); the word "guitar" derives from "qithara" as well.

Anton Karas (July 7, 1906 – January 10, 1985) was a Viennese zither player, best known for his soundtrack to Carol Reed's The Third Man.

Born in Vienna, of Hungarian and Czech origin, one of five children of a factory worker, Anton Karas was already keen on music as a child. He desired to become a band leader, which due to the family's financial situation was impossible. However, he was allowed to learn to play an instrument, as were his two brothers and two sisters. He later reported that his first zither was one he found in his grandmother's attic, at the age of 12.

As ordered by his father, he started an apprenticeship as a tool and die maker at the age of 14, while also taking music evening courses at a private institution. He successfully finished his apprenticeship in 1924 and worked in a car factory until being unemployed in January 1925. As he had already begun to study at the University of Music and Performing Arts, Vienna in 1924, he subsequently earned his living as an entertainer in a Heuriger (a wine bar, typically with a garden, usually selling the year's new wine) and soon found himself earning more income than his father. He continued his studies until 1928.