You might think, from their title, that superdelegates are better than regular delegates.
Actually, they’re worse.
The process for presidential elections in the United States is governed by the Constitution. Primary elections, however, are not. They are controlled by the political parties themselves. In fact, until the 1820s, members of Congress chose the presidential nominee for each party. That elitist system started to buckle with the advent of national conventions, though delegates were still selected through state and local convention processes controlled by the parties.
It wasn’t until the mid-1900s that parties embraced primary elections as part of the process for deciding on presidential candidates. But to ensure that the voters themselves didn’t have all the power, in 1982 the Democratic Party adopted what are called superdelegates, who today control 15% of the final nomination process.
The Republican Party has superdelegates, too, but they have a lot less power. GOP superdelegates are only about 7% of the nominating vote, and according to Republican convention rules, superdelegates must vote in accordance with their state primary outcomes.