What is batchim?

Hangeul is a phonetic alphabet like the English alphabet. Korean alphabet letters do not array in a row like the English alphabet. Instead, consonants and vowels are combined to make syllables, which is called "모아쓰기(Mo.a.sseu.gi)." "모아쓰기" in English can be translated into "Collective Writing." In "모아쓰기," the final consonant at the bottom of the middle vowel is called "받침(Batchim)".
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The basic pattern of syllables in Korean is "Initial(or First) Sound(consonant) + Middle Sound(vowel) + Final Sound(consonant). There are syllables consisting of only a vowel or syllables consisting of "Middle sound(vowel) + Final sound(consonant)". The consonant in the final sound position is called "받침(Batchim)". In other words , a consonant that is positioned at the end of a syllable is called the final sound or Batchim. Final sound, final consonant, and batchim are the same meaning.

"받침 (Batchim)" is a noun form of the verb "받치다(Batchida)," which means support or prop by positioning below the middle vowel. The shape of Korean syllables looks like a square box. According to the Standard Korean Dictionary, "받침" can be divided into three categories, "홑받침(Hotbatchim)," "쌍받침(Ssangbatchim)," and "겹받침(Gyeopbatchim)." "홑(Hot)" in "홑받침(Hotbatchim)" means "single". "홑받침" consists of single consonants such as, ‘ㄱ’, ‘ㄴ’, ‘ㄷ’, ‘ㄹ’, ‘ㅁ’, ‘ㅂ’, ‘ㅅ’, ‘ㅇ’, ‘ㅈ’, ‘ㅊ’, ‘ㅋ’, ‘ㅌ’, ‘ㅍ’, ‘ㅎ’.  "쌍(Ssang)" in "쌍받침(Ssangbatchim)" means "Double." There are only two ssangbatchim, 'ㄲ(ssanggiyeok)' and 'ㅆ(ssangsiot).'  "겹받침(Gyeopbatchim)" is similar to "쌍받침(ssangbatchim)" in that there are two paired consonants. But the two paired consonants are different, not like double consonants (ㄲ and ㅆ). There are 11 Gyeopbatchim, "ㄳ, ㄵ, ㄶ, ㄺ, ㄻ, ㄼ, ㄽ, ㄾ, ㄿ, ㅀ, ㅄ." ​

Gyeopbatchim is simply a combination of two different consonants and is not included in the consonant group of the Korean alphabet. From the Korean standard pronunciation rule, there are 19 consonants and 21 vowels in the Korean alphabet. According to modern Korean writing rule, most consonants except for some double consonants can be written in the final sound position, but only seven consonants(ㄱ, ㄴ, ㄷ, ㄹ, ㅁ, ㅂ, ㅇ) can be pronounced. So, when a consonant that does not belong to these seven consonants is placed in the final sound position, it is changed to one of these seven consonants. That is, when it comes to pronouncing "Batchim", only seven consonants "ㄱ, ㄴ, ㄷ, ㄹ, ㅁ, ㅂ, ㅇ" are pronounced as the Batchim sound in Korean. For example, when "ㄲ" is used as "Batchim," it is pronounced the same sound as "ㄱ" as shown in the table below. ​