Dear Aditya and Youssef Cherem,

To: Aditya,
> 
> There is the talk that Wolfgang gave in this year's context meeting:
> 
> https://meeting.contextgarden.net/2021/talks/2021-09-23/definefontfamily.pdf
> 
Thank you for letting me know the talk which gives me more understanding about \definefontfamily.

To: Youssef Cherem,

Recently, Wolfgang helped me to define a font family as following, and I hope that it gives you some idea to use \definefontfamily.

\definefallbackfamily [nanum] [rm] [Tex Gyre Pagella]
  [range={basiclatin,latinsupplement,latinextendeda,latinextendedb}, 
   force=yes]
\definefallbackfamily [nanum] [rm] [Noto Serif CJK KR]
  [range={cjkunifiedideographs},force=yes]
\definefontfamily [nanum] [rm] [Nanum Myeongjo OTF]
  [   it={style:regular,features:{*,slanted}},
      bi={style:bold,features:{*,slanted}},force=yes]

Explanation:
1. I use Korean font whose family name is “Nanum Myeongjo OTF” as main font. Since it doesn’t have italic style and bold italic style, I add [it=… , bi=…] to simulate the styles.

2. Since I want to use English character in "TeX Gyre Pagella”. I add it in the first \definefallbackfamily with an option [range={…},force=yes] which restrict the use of font to Latin characters.

3. We use chinese characters also in the Korean sentences. But "Nanum Myeongjo OTF” doesn’t have Chinese characters. So I add another font “Noto Serif CJK KR” which contains Chinese character with the option [range={cjkunified…},force=yes] in the second \definefallbackfamily.

There are two font families more,  sans and mono which is similar as rm.
It is really nice to use \definefontfamily which saves a lot of work to define fonts. 

Thanks Wolfgang.
If there are something should changed in the above definition, please tell me what to do.

Best regards,

Dalyoung