This is a quick reply to "Hiding text inside text" by Edwin Wagha: https://youtu.be/4LhL9ypdbQU
Edwin Wagha uses strings of 8 chars where each char is either ZWS (zero-width spacer) or ZWNJ (zero-width non-joiner) to represent any single-byte char.
This allows to encode 256 distinct characters using 256 distinct 8-char-strings.
Additionally ZWJ (zero-width joiner) is inserted before and after the secret message (to aid parsing).