If you've never heard the term 'dystopian fiction' before, or you're not quite sure whether a book you're about to read (or have just read) is dystopian in nature at all, here are the main characteristics that make it fit the genre quite well.
Dystopian literature is basically related to an utopian world (a perfect world so to speak) which is in one way or another totally distorted. It is a world that really nobody with its might in the right place would ever want to live in.
So unlike an utopian society, the dystopian society is a bad, bad place to be in. A twisted society where the government has everything but the well-being of the folks at heart.
Btw, if you're wondering, dystopian fiction has nothing to do (well, at least not much to do) with post-apocalyptic novels, which focuses on the end of the world and how people are struggling to live afterwards.
Here the society is actually the controlling enemy, and the main character is usually a rebellious person (or team) who tries to right a wrong by any means possible (remember in The Hunger Games, Catniss Everdeen became 'the mockingjay', the symbol for freedom from the cruel society they were living in).
So in a nutshell, a dystopian society is a futuristic society where humans have literally no rights. The novels take great care in highlighting the major flows of such societies, and in a way they even sent warning signals - these things can actually happen and it's not all that unusual to image a future just like it.
In general the modern dystopian fiction is made of 3 books, and most books reviews above are a trilogy indeed (even Host will have 2 more novels under its name). While there are many like it, the first thing most people's minds go to when thinking of modern dystopia is indeed The Hunger Games. While dystopian fiction existed for quite some time before it, I think this series has totally revolutionized the genre, and there are now many copy-cats (some better, some worse) that want to reach the fame and popularity of this trilogy.
Did you know that one of the earliest classic dystopian novels is H.G. Well's The Time Machine, which is classified as science fiction, with a fully dystopian society in action. So the genre is nothing new, but The Hunger Games really made it popular and sought out among readers.