About “hello world“:
A “hello world” program is a computer program that prints out “Hello, World!” on a display device.
A “hello world” program can be a useful sanity test to make sure that a language’s compiler, development environment, and run-time environment are correctly installed.
While small test programs existed since the development of programmable computers, the tradition of using the phrase “Hello world!” as a test message was influenced by an example program in the book The C Programming Language. The example program from that book prints “hello, world” (without capital letters or exclamation mark), and was inherited from a 1974 Bell Laboratories internal memorandum by Brian Kernighan, Programming in C: A Tutorial, which contains the first known version: