This kana is derived from the base katakana 『ツ』 (tsu) with a dakuten (゛) added, representing the sound 'zu'. It is used in native Japanese words and loanwords, but note that in modern Japanese, 『ズ』 (zu) is more common for the 'zu' sound, while 『ヅ』 often appears in specific contexts or words where it retains its original usage. For example, in the word 『つづく』 (tsuzuku, 'to continue'), the hiragana version uses 『づ』, and the katakana equivalent might use 『ヅ』 in some contexts, though it's rare. In katakana, it's typically found in older or specialized terms.