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Below is a unicode chart for Hiragana characters. I see there are two a, i, u, e, o and so on, small and big ones. Please help me explain this as I am just starting to learn Hiragana today.
I got this unicode chart from this page.
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Certain sounds in Japanese are spelled with two characters, much like in English spellings like the "sh" in "fish" to spell the sound //ʃ//. These combinations are called digraphs. There was a separate post about a related issue over here that provides more detail.
The large/normal size and small size characters for hiragana and katakana have different Unicode representations.
Sometimes small kana are combined with normal kana to represent certain sounds. The most typical types are listed below:
拗音{ようおん}: Contracted sounds like sha, kya, gyo, etc are represented with one normal sized and one small kana character. For example, しゃ, きゃ, ぎょ, etc.
促音{そくおん}: Used to mark a geminate consonant - this is represented with a small tsu. For example, きって.
外来語{がいらいご}: Words borrowed from foreign languages. It is often not possible to represent sounds from foreign languages with standard kana use, so the vowel sounds are often combined with various consonants in an attempt to authentically recreate the original sound. Again, very often you see a normal sized character and a small character together. There are many, but for example, fa = ファ, ti = ティ, 'doo' =ドゥ, etc.
