How is Unicode replacement possible?

Question

Programming

Good afternoon, tell me, is there a unicode of the alphabet, there is a unicode of pictures, icons and other things.
How is it that after replacing letters with symbols, the code works?

Answer 1

Obviously, the programming language translator is quite liberal about "what an identifier is". And all these emoticons and shit (yy, shit emoji appeared not so long ago) are also considered letters. However, there is a small trap here: if you compose the same character in different ways - for example, "and + short" against a monolithic "y" - these will be different identifiers.
UPD. See how it's done in Java. Any character that is a Unicode letter will do. At least according to Gosling's specification.