This is an answer-chaining challenge in which each answer builds on the previous answer. I recommend sorting the thread by "oldest" in order to be sure about the order in which the posts ...
This entire 12 page thread was one hell of a journey. And language 340 was added just a few days ago, so it’s still active!
Basically, clever use of syntax so the programming can be run as more than one language.
As a basic example, consider that the # symbol means a preprocessor statement in C, but a comment in Python. You can take advantage of this by writing a Python program, and then using the preprocessor to redefine the Python parts to C code. When executed in Python, all the preprocessor statements will be ignored, and when executed in C, the redefines turn the Python code into C code.
Or as an even more basic example, print("Hello world!") is valid in more than one language. So it’s already a polyglot.
Basically, clever use of syntax so the programming can be run as more than one language.
As a basic example, consider that the # symbol means a preprocessor statement in C, but a comment in Python. You can take advantage of this by writing a Python program, and then using the preprocessor to redefine the Python parts to C code. When executed in Python, all the preprocessor statements will be ignored, and when executed in C, the redefines turn the Python code into C code.
Or as an even more basic example,
print("Hello world!")is valid in more than one language. So it’s already a polyglot.