Hangul letters and digraphs are called jamo (자모; 字母) or natsori (낱소리). There are 24 letters and 27 digraphs (and sometimes trigraphs) formed from these letters in the modern alphabet. Of the letters, fourteen are consonants (ja-eum 자음, 子音 "child sounds") and ten are vowels (mo-eum 모음, 母音 "mother sounds"). Five of the consonants are doubled to form the five "tense" (faucalized) consonants of Korean (see below), while another eleven sequences are formed of two different consonants. The ten vowel letters are combined into eleven sequences for diphthongs.
Source = http://en.wikipedia.org/wiki/Hangul http://en.wikipedia.org/wiki/Hangul_consonant_and_vowel_tables http://ko.wikipedia.org/wiki/%ED%95%9C%EA%B8%80