> For the complete documentation index, see [llms.txt](https://www.i18next.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://www.i18next.com/principles.md).

# Principles

- [Best Practices](https://www.i18next.com/principles/best-practices.md): Best practices for translatable code: keep sentences whole, avoid string concatenation, use interpolation, plurals and context, and name keys semantically.
- [Translation Resolution](https://www.i18next.com/principles/translation-resolution.md): How i18next resolves a key: the order of languages, namespaces, context, plurals and fallbacks it tries before returning a value or the key itself.
- [Namespaces](https://www.i18next.com/principles/namespaces.md): Split translations into namespaces (multiple files), load them on demand, and set the default and fallback namespace.
- [Fallback](https://www.i18next.com/principles/fallback.md): Fallback behavior in i18next: fallback languages, fallback namespaces, fallback keys and default values, and what a raw key in the UI means.
- [Plugins](https://www.i18next.com/principles/plugins.md): How i18next plugins work: backends, language detectors, post processors, i18n formats and third-party modules, and how they are registered with use().