@xianc78Basically it was a Imperial state that covered much of Central/Western Europe. Basically it was a Empire ordained by the Catholic church making it both holy and Roman. Although the Imperial entity would change over time and wax an wane as most empires did.
@dharmadudebro Well, there's modern education for you. I remember it just being a footnote in our history books in high-school but couldn't remember the details.
Basically it was just the first Reich. The Holy Roman Emperor was the protector of the Church which gave him a special status above other Kings of Europe. It was made up of Germany, most of Italy, Bohemia and Austria although territories changed hands throughout its 1000 year history. The Emperor had to be elected from amongst the many kings of the Empire but after about the 1600s the House of Habsburg had a monopoly on the imperial throne. It basically ceased to exist as anything but an empire on paper after the Napoleonic wars.
This guy does really good videos on the subject if your are interested.