Refers to a writing system or layout direction where text begins at the right side of a page or screen and proceeds to the left. This is the inverse of the Left-to-Right (LTR) direction used in Latin-based scripts like English. In digital design, RTL involves not only text flow but also mirroring user interface elements to match the reader’s optical path.
RTL Language and Script Context
Common languages that utilize RTL scripts include:
- Arabic
- Hebrew
- Persian (Farsi)
- Urdu
- Pashto
- Yiddish
RTL Concepts
Bidirectionality (BiDi)
Most RTL documents are actually bidirectional. While the primary script flows right-to-left, certain elements—such as Western numbers (123), URLs, or embedded English words maintain their LTR orientation. Software must use the Unicode Bidirectional Algorithm to display these mixed sequences correctly.
UI Mirroring
In an RTL layout, the entire visual hierarchy is typically flipped to maintain a natural reading gravity.
- Start and End: In RTL, Start is the right and End is the left.
- Layout Flow: Sidebars, navigation menus, and form labels shift from the left to the right.
- Directional Icons: Arrows indicating back or forward are mirrored to reflect the direction of time or progress (e.g., a back arrow points right).
Typography and Spacing
RTL scripts often require specific typographic adjustments:
- Line Height: Scripts such as Arabic feature tall characters and complex diacritics, often requiring more vertical space between lines than Latin text.
- Calligraphic Styles: RTL fonts often emphasize horizontal connectivity (kashida) rather than the blocky, individual character spacing seen in Western typography.
Technical Indicators
| Feature | RTL Behavior |
| Primary Alignment | Right-aligned |
| Scroll Direction | Horizontal overflow typically scrolls toward the left |
| Progress Bars | Fill from right to left |
| Numbers | Read and written Left-to-Right (even within RTL sentences) |
