亂碼既疑惑. 亂碼d字係點形成呢? ( 10分! )

For some web site, they use the unicode/utf-8 for the encoding, big-5(繁) and GB(簡), so when you choose to view either big-5 and GB code in utf-8 format, then you get 亂碼, similar to the opposite way.

邊個發明?
no one, since 亂碼 is a corrupted code which could not find the right character for display.

All chinese char you can read or view were translated from your windows code table, for example
language1 => ab=1 ac=2 ad=3 (2 digits map to 1 char),
language2 => a =1 b= 2 c=3 d=4
language3 => aba=? cad=#
e.g. if you have a sentence written as 123 and the code behind was abacad, when you use the 1 digit code table to read the sentence then it won't show 123 anymore, and it will try to map a=1 b=2 a=1 c=3 a=1 d=4 from the 1-digit code table becomes 121314. Similar if you use the 3-digit format to map the abacad, it becomes aba=? cad=#, for sure it won't display 123, but some other stuff, that's the 亂碼.

Therefore, for the original sentence 123, when you using different encoding format, it show different things
123 becomes 121314
or 123 becomes ?#