Updated : 
 I remember reading this book a week before my final exam, i mean when students are supposed to be preparing for exams, i was busy reading divergent, but i got good grades anyway (cuz i cheated in the test) 
 No, just kidding :) 
 The book: 
 Divergent tells the story of a society divided to 5 factions, each faction is known for a certain thing: 
 Factions: 
 Abnegation: selflessness 
 Dauntless: bravery 
 Erudite: intelligence 
 Candor: honesty/justice 
 Amity: peace 
 When the members of the society turn 16 years old, they are supposed to choose a faction that defines them best, and you have to leave you family and the faction you were born in if you chose another faction, as the book says: 
 "Faction before blood" 
 but what if ONE faction can't define you, what if you are selfless, smart, brave, honest and peaceful at the same time??? 
 Then you are a divergent dear friend, and being one comes with a price, DEATH!! 
 The Movie: 
 The movie was soooo fast, i have to say that i watched the movie before reading the book and i didn't understand few things, i was like "why they're doing that" so i decided to read the book. 
 After reading the book i must say that the book was better. There were few things in the book that that were not the same in the movie like the death of The first Dauntless initiate who jumps off the train, and that was a very important thing because it's the first thing that tells you "hey, dauntless is not a joke" 
 The other thing is that in the book Edward gets stabbed in the eye which is a very important thing, because it describes the character of Peter and the real jerk he is. I mean he's still a jerk in the movie but if you read the book you will hate him more. 
 And the last thing is that the directors decided to exclude the character of Uriah which will become a very important character later. But overall the adaptation was good in its own way.