It was the American military to promote its own internal communications, and scientific research. Al Gore, then a Senator, along with the of the Congress voted to authorize the military to open it up to civilian use, though since it was used to communicate with civilian scientists it had been somewhat demilitarized already.
THe World Wide Web was invented by some Swiss scientists looking for a better way to use the “internet”. Previously (and if you don’t use a graphic brower, even today), the internet was largely for text email and sending files (the ftp system).
Arguably the origin of the internet was the telegraph invented in the early 19th century (which at the time caused complaints about its social impact not unlike those heard about the internet today, e.g. female telegraph operators “chatting” with male telegraph operators).