The cover of the book says 'One choice can transform you' and based on the transformations of character that go on during this book, it couldn't be more right. The world of Divergent is one that is not fully explained until the second book. I've been told that the world seems a bit unbelievable, I can see that point of view at the beginning, but as the series progresses, the background of their city and five factions become infinitely clear. The five factions are Abnegation, the selfless, Candor, the truthful, Dauntless, the brave, Amity, the peaceful, and Erudite, the intelligent. The one thing I see wrong with this picture is that, how can a person be classified to just one faction. I could be in any of the above factions, but wouldn't thrive in any one because I'm a bit of everything. The main character very much embodies the fact that you can't be classified into one thing in life.
The main character is Beatrice 'Tris' Prior. She began in Abnegation, but changes to Dauntless in the beginning after learning that she's Divergent. Meaning she can belong to multiple factions. She faces many challenges, including fierce competition, hiding her secret of being Divergent-for telling anyone could endanger her life-and her budding romance with the trainer of the Dauntless initiates, Four (don't worry, he's only a couple years older than her).
There are some fairly obvious things in the book. Little things mentioned at the beginning that are built on later on. Let me tell you this, nothing is coincidence. The story gets better and more intricate with every page. I gobbled it up in just about one sitting. It's a book of choices and not being confined to one lifestyle. While it's a book purely for entertainment, it seems to have some moral things in there as well.