When an alphabet is borrowed from its original language for use with a new language—as has been done with the Latin alphabet for many languages, or Japanese Katakana for non-Japanese words—it often proves defective in representing the new language's phonemes. Sometimes this problem is addressed by the use of such devices as digraphs (such as "sh" and "ch" in English, where pairs of letters represent single sounds), diacritics (like the caron on the letters "š" and "č", which represent those same sounds in Czech), or the addition of completely new symbols (as some languages have introduced the letter "w" to the Latin alphabet) or of symbols from another alphabet, such as the rune "þ" in Icelandic.