Zoran Luledzija
Zoran Luledzija
April 11, 2023
5 min read
April 11, 2023
5 min read

Language vs Locale: Understanding the key differences for better software localization

Language vs Locale

In today's globalized world, the success of a software product often depends on its ability to cater to diverse audiences with varying linguistic and cultural backgrounds. Understanding the key differences between language and locale is essential for creating products that resonate with your target users, regardless of their location. This is where the concept of software localization comes into play, a process that goes beyond mere translation to adapting a product's interface, content, and overall user experience to meet the specific needs of different regions.

In this blog post, we will delve into the intricacies of language and locale, two terms that are often used interchangeably but have distinct meanings and implications in the world of software development.

What is language?

Language is a complex system of communication that allows individuals to convey ideas, thoughts, and emotions through symbols, sounds, and gestures. It is an essential tool for human interaction, enabling people to collaborate, learn, and express themselves. Languages come in many forms, including spoken, written, and signed varieties.

There are several thousand languages spoken worldwide, each with its own unique vocabulary, grammar, and pronunciation. Some well-known examples include English, Spanish, Mandarin, Hindi, Arabic, Chinese, French, German, and Japanese. These languages vary greatly in the number of speakers, geographic distribution, and historical development.

To facilitate clear identification and classification, languages are assigned codes according to international standards. The most widely used system for language representation is the ISO 639 series of standards, which provide two- and three-letter codes for languages. ISO 639-1 is the most common, consisting of two-letter codes that represent languages in a concise and easily recognizable format. For instance, "en" stands for English, "es" for Spanish, and "zh" for Chinese. These codes are instrumental in various applications, such as software localization and international communication, allowing for a standardized way to reference languages across different platforms and systems.

What is locale?

A locale is a specific combination of language, region, script, and other cultural elements that together define the preferences and conventions for a particular user group or geographical area. It is an essential concept in software development, as it helps developers create applications that can be tailored to the specific needs of users from different cultural backgrounds, ensuring a more inclusive and user-friendly experience.

The components of a locale are:

  • Language: The primary language spoken by the user group or in the geographical area, represented by a two-letter code according to the ISO 639-1 standard (e.g., "en" for English or "fr" for French).
  • Region (optional): The country or region where the user group is located, represented by a two-letter code according to the ISO 3166-1 standard (e.g., "US" for the United States or "FR" for France).
  • Script (optional): The writing system used for the language, which is especially important for languages that use multiple scripts (e.g., "Latn" for Latin script or "Cyrl" for Cyrillic script).

Locale codes are typically formed by combining the ISO 639-1 language code and the ISO 3166-1 region code, separated by an underscore or a hyphen. For example, "en_US" or "en-US" represent English as spoken in the United States, while "fr_CA" or "fr-CA" represent French as spoken in Canada.

Note: Different programming languages and software systems may have varying approaches to defining locales and their components. While the core components language, region, and sometimes script are generally present across various systems, they might be named differently or have additional parameters. For instance, some systems may use the term "country" instead of "region" or include other elements.

Differences between language and locale

Language and locale are two distinct yet related concepts in software development. Language refers to a system of communication, such as English, Spanish, or Mandarin, while locale encompasses not only the language but also the region and other cultural elements that define the preferences and conventions of a specific user group or geographical area, such as date formats, time formats, and currency symbols.

In software development, understanding the difference between language and locale is crucial for creating applications that cater to users from various cultural backgrounds. While language broadly identifies the mode of communication, locale allows developers to customize the application's behavior and appearance according to the specific linguistic and cultural needs of the target audience, ensuring a more inclusive and user-friendly experience.

The following examples showcase British English ("en-GB") and American English ("en-US"), highlighting the language variations when English is spoken in different countries. Although it's the same language, cultural differences and factors like distinct currencies lead to adaptations in the text.

  • "Nice colour!""Nice color!"
  • "I like biscuits.""I like cookies."
  • "Rent a flat.""Rent an apartment."
  • "Admission is £8.04.""Admission is $10."

Usage of locales in software localization

In software localization, using locales instead of just languages offers a more comprehensive approach to catering to diverse user preferences. Locales take into account not only the language but also regional variations and other cultural aspects, such as date and time formats, currency symbols, and metric systems. This additional information enables a more tailored and accurate representation of user preferences.

By leveraging localization libraries, developers can automatically adapt these formatting conventions based on the specified locale, without the need to manually consider every detail during the software localization phase. This streamlines the development process, saves time, and ensures a more consistent and user-friendly experience for users from different cultural backgrounds.

Dashes and underscores in locale representation

Dashes and underscores are both used in locale representation, resulting in two different formats: "en-US" (with a dash) and "en_US" (with an underscore). The existence of these two formats can be attributed to varying conventions and requirements across programming languages, libraries, and software systems.

The compatibility and conversion between dashes and underscores are essential for maintaining consistency and avoiding potential issues when working with different systems or localization libraries. Some libraries strictly rely on one representation, and using the incorrect format may lead to bugs or unexpected behavior in the software. Consequently, developers must be cautious and adapt the representation to match the specific requirements of the localization library or framework they are using.


Understanding the key differences between language and locale is crucial for effective software localization. While language refers to a system of communication, locale encompasses the language, region, and other cultural elements that define the preferences and conventions of a specific user group or geographical area. By acknowledging these distinctions, developers can create more inclusive and user-friendly applications that cater to diverse linguistic and cultural needs.

Embracing the power of locales in software localization allows developers to automatically adapt formatting conventions, such as dates, times, currencies, and metrics, with the help of localization libraries. This streamlined approach not only saves time but also ensures a consistent user experience across different cultural backgrounds.

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Zoran Luledzija
Zoran Luledzija

Zoran is a Software Engineer at Localizely. His primary interest is web development, but he also has a solid background in other technologies. For the last few years, he has been involved in the development of software localization tools.

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