Working with Languages. Basic concepts.

Valid for Sitecore 5.3

Control Panel » Globalization page provides tasks for working with languages.

Below is the list of things users should NOT do via the Content Editor:

Delete a Language item.
Doing so may have unintended side-effects.
Archive a Language Item.
The effect is the same as deleting the item.
Move a language item outside /Sitecore/system/Languages.
The effect is the same as deleting the item.
Make multiple versions of the Language item.
Hide the item.
The effect is the same as deleting the item.

The list of things users should do via the Content Editor:

Set Display Name.
It is not recommended to rename a language item, but you may set the Display Name property to give the languages their natural names:

Note: the Display Name property does not affect the way the language is named when you click the language icon ( ) – this name is selected according the the ISO code.
Set Security.
For example, if users do not have write access to the Language Item, they do not have write access to content in the given language.

Do with caution:

Add a new language via the Content Editor.
The Control Panel » Globalization page offers the preferred approach for this action, but users may also add a new language manually via the Content Editor.
Use the _Language master assigned to the /sitecore/system/languages item.

Unlike the wizard available via the Control Panel, however, creating a new language in this way does not request values for required fields.
Rename a Language item.
Such operation will trigger language renaming operation on all items which contain this language. There is a setting in web.config that handles renaming:

<setting name="Languages.AutoRenameItemData" value="true" />

The Globalization page of the Control Panel provides convenient functionality for managing languages, for instance – for deleting a language.