The term can be pretty broad. In terms of what's used in practice, it's generally elected representatives or parties.
China's a pretty interesting counter-example. I don't know very much about their government unfortunately, beyond what tends to make the news.
* No votes, just voluntary interactions
* The people voting on every issue
* The government/representatives being chosen randomly from the people
* Elected representatives being voted for by the people
* Political parties being voted for by the people
Then you have more details like franchise, denizens vs citizens, bicameralism, and more to worry about.
I would also say China today is neither a democracy (as least as you would think) or an autocracy.