locale (site language) (tag)

determine_locale()

Gets the current site locale (site language, ex, en_US) desired for the request.

get_locale()

Sets the global variable $locale and gets the current site locale (for example, en_US).

get_user_locale()

Gets the locale (translation language) of the current or specified user. It will return the value of get_locale() if the user has not set a separate locale in their profile.

is_locale_switched()

Checks if the locale (translation language) has been switched, whether the switch_to_locale() function has been used.

sanitize_locale_name()

Removes all characters that are not allowed in the locale name.

switch_to_locale()

Allows you to programmatically switch the site's language.