Wikipedia
In a right-to-left, top-to-bottom script (commonly shortened to right to left or abbreviated RTL), writing starts from the right of the page and continues to the left.
Arabic script is the most widespread RTL writing system in modern times. As usage of the script spread, the repertoire of 28 characters used to write Arabic language was supplemented to accommodate the sounds of many other languages such as Persian, Pashto, etc.
Several languages have both Arabic RTL and non-Arabic LTR writing systems. For example, Sindhi is commonly written in Arabic and Devanagari scripts, and a number of others have been used. Kurdish may be written in Arabic, Latin, Cyrillic or Armenian script.
Hebrew, Syriac, and Mandaean (Mandaic) scripts are, like Arabic, derived from Aramaic and are written RTL. Samaritan is similar, but developed from Proto-Hebrew rather than Aramaic. Many other ancient and historic scripts derived from Aramic and inherited its right-to-left direction.
Taana appeared around 1600 CE. Most modern scripts are LTR, but the African scripts N'Ko (1949), Mende Kikakui (19th century), and Adlam (1980s) were created in modern times and are RTL.
Ancient examples of text using alphabets such as Phoenician, Greek, or Old Italic may exist variously in left-to-right, right-to-left, or boustrophedon order; so it's not always possible to classify some ancient writing systems as purely RTL or LTR.
Right-to-left can also refer to (TB-RL or TBRL) scripts such as Chinese, Japanese, and Korean, though they are also commonly written . Books designed for predominately TBRL vertical text open in the same direction as those for RLTB horizontal text: the spine is on the right and pages are numbered from right-to-left.