---
title: "Internationalization and Localization"
source: Microsoft Code-With Engineering Playbook
source_url: https://github.com/microsoft/code-with-engineering-playbook
licence: CC-BY-4.0
domain: engineering
subdomain: microsoft-code-with-playbook
date_added: 2026-04-25
---

# Internationalization and Localization

Internationalization (i18n) and Localization (l10n) refer to the design and adaptation of software systems to support multiple languages, cultures, and regions, ensuring usability and compliance with local preferences and regulations.

## Characteristics

### Main Characteristics of Internationalization

- Text Externalization: Moving all user-facing text to external resource files to facilitate easy translation.
- Unicode Support: Using Unicode or another character encoding that supports all necessary scripts and characters.
- Date and Time Formatting: Designing the system to handle various date and time formats.
- Number and Currency Formatting: Ensuring that numbers and currencies can be displayed according to local conventions.
- Locale-Sensitive Data Processing: Adapting data processing to respect locale-specific rules, such as sorting and case conversion.
- Bidirectional Text Support: Supporting both left-to-right (LTR) and right-to-left (RTL) text orientations where necessary.

### Main Characteristics of Localization

- Translation: Converting text and UI elements to the target language.
- Cultural Adaptation: Adapting content and design elements to align with local cultural norms and expectations.
- Legal and Regulatory Compliance: Ensuring that the application meets local legal requirements, such as privacy laws and accessibility standards.
- Testing in Context: Testing the localized version of the application in its intended locale to ensure proper functionality and usability.
- Localized User Interfaces: Adjusting the layout and design to accommodate text expansion or contraction and to suit cultural preferences.
- Help and Documentation: Providing user assistance and documentation in the target language and context.

## Implementations

- Resource Bundles: Using resource bundles to store locale-specific text and data.
- Translation Management Systems: Employing tools and platforms to manage translations and streamline the localization workflow.
- Locale-Aware Libraries: Leveraging libraries and frameworks that provide built-in support for handling locale-specific data.
- Automated Testing: Implementing automated tests to verify that the software behaves correctly in different locales.
- Continuous Localization: Integrating localization processes into the continuous integration/continuous deployment (CI/CD) pipeline to keep translations up-to-date.
- Coordinated Universal Time: When dealing with times, it is essential to always use UTC for internal storage and processing. Using UTC helps avoid issues related to time zone differences, daylight saving time changes, and other regional time adjustments.
- Consistent Internal Representation: Store numbers and currency values in a consistent internal representation, such as a standardized numeric format or a base currency, and apply locale-specific formatting only when displaying data to the user. This prevents errors during calculations and data processing.
