3 Computer programs that have changed the world

Linux? BSD would have filled that void, if Linus hadn't written it.

GCC? The portable C compiler already was years old, and would have gotten more attention if it hadn't taken over.

Web Browser? That's big enough an improvement over gopher to be something genuinely new. The world would look different without it.

I would consider adding email, Word processing, VisiCalc and the first 'real' search engine, whatever that was.

I would consider the GPL idea, too, but that's not software, but wetware.

Click bait. It would be nice if HN were to filter out this sort of SPAM.