Transliteration provides a central transliteration (romanization) service to other Drupal modules, and cleans file names during upload by replacing unwanted characters.
Generally spoken, it takes Unicode text and tries to represent it in US-ASCII characters (universally displayable, unaccented characters) by attempting to transliterate the pronunciation expressed by the text in some other writing system to Roman letters.
According to Unidecode, from which most of the transliteration data has been derived, "Russian and Greek seem to work passably. But it works quite bad on Japanese and Thai."
In Drupal 8 core
Transliteration is part of Drupal 8 core. See #567832: Transliteration in core.
If you are installing to an existing Drupal site, you might want to fix existing file names after installation, which will update all file names containing non-ASCII characters. However, if you have manually entered links to those files in any contents, these links will break since the original files are renamed. Therefore it is a good idea to test the conversion first on a copy of your web site. You'll find the retroactive conversion at Configuration and modules >> Media >> File system >> Transliteration.
This page is a placeholder / pointer to the thoughtful “WYS(is not always)WYG(but it can be)” documentation by Andrew Mallis on Google Docs, which deals with configuration options of WYSIWYG editors, role management, image handling and file organisation for a better user experience.
The discussed configuration is also available via distribution profile on gitHub.Read more