Although the Domain Name System supports non-ASCII characters, applications such as e-mail and web browsers restrict the characters which can be used as domain names for purposes such as a hostname. Strictly speaking, it is the network protocols these applications use that have restrictions on the characters which can be used in domain names, not the applications that have these limitations or the DNS itself. To retain backwards compatibility with the installed base, the IETF IDNA Working Group decided that internationalized domain names should be converted to a suitable ASCII-based form that could be handled by web browsers and other user applications. IDNA specifies how this conversion between names written in non-ASCII characters and their ASCII-based representation is performed.