Hello World is, traditionally, the first computer program that programmers will build when learning a new programming language. It is a small program that is intended to give the new programmer a chance to learn how to get the computer to print something on the screen. In the case of Hello World, it is the text "Hello World!"
While the origin of Hello World is shrouded in the mists of time, the first written record to be found is from a 1972 book by Brian Kernighan. Whatever the true origin of the Hello World program is, it has become a tradition for programmers to be the first program written; whether they are learning a new computer language or teaching new programmers.
When I was a kid in the 1980's I was in the post exchange on the military base in Spokane, Washington, looking at the new Commodore 64 that had just come out and was on display in the electronics department. I was admiring it from afar, because two soldiers were already examining the computer. They left it, in a bit of a hurry, and I headed over to examine it. Turns out they had messed something up and accidently closed the demo program that the store had run on the computer.
Well, my dad had taught me BASIC and C+ on the Vic-20 we owned, so I started typing on the prompt and wrote a small Hello World! program. Pleased with that I kept typing and it was about that time that I realized that the two soldiers had stopped in the nearby furniture section and were feigning looking at a couch while they watched me, a 12 year old kid, tapping away at the computer they had just "broke".
Finally finished with my little program, I wandered off to look for my mom somewhere shopping in the PX and will admit I felt a bit of self pride as I watched those two GIs scramble back over to see what I had been working on. I sort of wish I had stayed to see what they thought of the computer saying "Hello World! I am the Commodore 64, what is your name?"
I had set it up to ask the person's name, then to go into a questions and answers loop where it would ask questions so that it could learn from the user. If it responded wrong to the user it would ask what the correct response should have been, then stored the answer in its memory so that it knew how to respond the next time it came to that question.
I have, unfortunately, got out of programming over the years, but dive back in on occasion and have recently began learning C++.