In computing, quine is a program that produces its complete source code as its only output. For amusement, programmers sometimes attempt to develop the shortest possible quine in any given programming language.
Note that authoring the program to seek out and read its own source file to print is considered cheating.
Quines are named after philosopher Willard Van Orman Quine (1908–2000), who made an extensive study of indirect self-reference. He coined, among others, the following paradox-producing expression, known as Quine’s paradox: “‘Yields falsehood when preceded by its quotation’ yields falsehood when preceded by its quotation.”
Here’s one example of a quine in BASIC: