Some writing systems of the world, such as Arabic, Farsi, Urdu and Hebrew, are written in a form known as right-to-left (RTL), in which writing begins at the right-hand side of a page and concludes at the left-hand side. This is different from the left-to-right (LTR) direction in which languages using the Latin alphabet (such as English) are written. When LTR text is mixed with RTL in the same paragraph, each type of text should be written in its own direction, which is known as bi-directional text. This can get rather complex when multiple levels of quotation are used. Almost all writing systems originating in the Middle East are of this nature.
Bidirectional script support is the capability of a computer system to correctly display bi-directional text. The term is often shortened to the jargon term BiDi or bidi.