This kana is derived from the base katakana 『ト』 (to) with a dakuten (゛) added, representing the sound 'do'. It is frequently used in loanwords and native Japanese words written in katakana. In some contexts, it can appear in grammatical particles when written in hiragana as 『ど』, but in katakana, it is primarily part of vocabulary. For example, in the word 『ドア』 (doa, 'door'), it is used within the word.