Origin of Hangul
Ledyard holds that the Koreans adopted five core consonant letters from ’Phags-pa, namely ㄱ "g" , ㄷ "d" , ㅂ "b" , ㅈ "j" , and ㄹ "l" . These were the consonants basic to Chinese phonology, rather than the graphically simplest letters (ㄱ "g" , ㄴ "n" , ㅁ "m" , and ㅅ "s" ) taken as the starting point by the "Haerye." A sixth letter, the null initial ㅇ, was invented by Sejong. The rest of the consonants were developed through featural derivation from these six, essentially as described in the "Haerye"; a resemblance to speech organs was an additional motivating factor in selecting the shapes of both the basic letters and their derivatives.
Hangul orthography
한글맞춤법 (Hangeul matchumbeop) refers to the overall rules of writing the Korean language with Hangul. The current orthography was issued and established by Korean Ministry of Culture in 1998. The first of it is Hunminjungeum(훈민정음). In everyday conversation, 한글 맞춤법 is referred to as 맞춤법.