How to install languages in Joomla?

Goal

Install an additional language in Joomla and set it as the default.

Steps (Joomla 4/5)

1. Enter the Joomla administration panel.
2. Go to System > Install > Languages.
3. Search for the language you need and click Install.
4. Go to System > Manage > Content Languages and confirm it is enabled.
5. In System > Manage > Languages, set the default language for:
   • Site (public site)
   • Administrator (panel)

Validation

• The frontend appears in the selected language.
• The admin panel shows the correct language.
• No extensions are missing critical language strings.

Official resources

• https://docs.joomla.org

Recommended readings

• How do I install Joomla?
• How to fix Internal Server Error 500 error?