Bidirectional languages (BiDi)

Bidirectional languages (BiDi) are languages that incorporate both left-to-right (LTR) and right-to-left (RTL) text directionality within the same document or segment of text. This feature is common in languages such as Arabic, Hebrew, Persian, and Urdu, where the primary script is written RTL, but may include LTR text for numbers, technical terms, punctuation marks, or embedded foreign words.

If you work on software development, localization, and web design, you need to understand how to manage bidirectional text, making sure that it is displayed correctly and remains readable across different platforms and devices.

🔄 Key points about bidirectional languages: #️⃣

• Text directionality: BiDi languages switch between RTL and LTR text directions, requiring careful handling to maintain readability and coherence.
• Common BiDi languages: Examples include Arabic, Hebrew, Persian, and Urdu, which predominantly use RTL scripts but integrate LTR text for specific elements.
• Technical considerations: Implementing support for BiDi languages involves using Unicode standards and BiDi algorithms to correctly render text directionality.
• User interface design: Designing user interfaces (UIs) that accommodate BiDi text with flexible layouts that can handle both RTL and LTR text is essential.
• Localization challenges: Translating content into BiDi languages requires expertise in target languages and cultural context to preserve the meaning and functionality of the original content.

🖥️ BiDi in interfaces and product design #️⃣

RTL support often affects the entire interface, not just text. Menus, navigation drawers, sidebars, breadcrumbs, and directional arrows usually need to mirror. At the same time, elements such as media controls, clocks, timelines, and some charts should keep their original direction, which makes BiDi layouts more complex than simple RTL text support.

This is why BiDi testing is a major part of localization QA for products that support Arabic or Hebrew interfaces.

🛠️ How teams support BiDi correctly #️⃣

• Use the dir="rtl" attribute in HTML
• Follow the Unicode Bidirectional Algorithm for mixed-direction strings
• Test with real RTL locales on physical devices
• Verify which icons and controls should mirror and which should not
• Review builds with native RTL speakers to catch subtle layout and UX issues

Developers and localizers can create inclusive and accessible digital experiences by learning to work with bidirectional text.