Unrestrained democracy, yes. Tyranny.

People need to understand that having a majority opinion does not inherently give you the right to impose that opinion on everyone else. Such impositions must be done with extreme hesitancy and restraint.

That's why many democratic countries have a constitution which prevents the government from restricting certain individual rights even in the face of popular opinion. But ultimately, the constitution is just a piece of paper. If people are determined to impose their will on others, it can only do so much.

The slave aristocracy of the Confederate States of America, and members only Communist Party of China are both democracies.

What we consider democracy went through a LOT of iteration, and continues to this day. Representative first-past-the-post is a form of democracy that can have the unfortunate side effect of the minority of the electorate establishing a tyranny of the majority. There is a lot of scholarship on how to make democratic systems more democratic.

Yes? Democracy is essentially exactly that - tyranny of the majority. The reason why successful democracies have so many checks and balances, constitutions that uphold essential rights etc is because of this fact. Really the main benefit of democracy is that it prevents the government from doing things which are wildly unpopular. To the extent that it "gives the people power", that is neutered as much as possible to prevent the majority from going "hey, we don't want these people here" and committing democratic genocide or whatever.

Not necessarily.

You can democratically trample the rights of minority groups.

Since it hasn't been linked in the tree of replies here, I'll add this for others: https://en.wikipedia.org/wiki/Tyranny_of_the_majority