As best as I can describe it from watching the movies...is that Harry...is hated by the evilest of evil characters, Voldemort, because Harry is the only person he ever tried to kill and was unsuccessful in doing so.
Voldemort was prevented from killing Harry because he was protected by the sacrifice of his mother. Harry's mother sacrificed herself...gave her life for Harry...and because of that Harry was "marked" (the scar on his forehead) and Voldemort was unable to touch him.
Voldemort started off as a kid in school but he was bad and thru years of making selfish choices he grew into the most evil person in that world.
There are 3 unforgivable curses. And, the death curse does something to the person who uses it. If you kill someone, you lose a piece of your own soul. Voldemort, in his effort to become immortal, took the torn pieces of his soul and put them in things in order that part of his soul would remain alive and unless all 7 of these pieces were destroyed he could remain alive.
What Voldemort hadn't planned on was that one of these pieces, called a horcrux, was actually in Harry.
All though out all the movies Voldemort is in some way trying to return and trying to take over the world, and kill Harry, basically. All of the conflict in each movie is somehow related to that.
Voldemort has an evil following who are mingled in everywhere. His followers are pretty obvious because they are not kind people. One of his followers, Draco's father who has led his entire family into a life of misery, we get to see in the end realizes that following an evil leader isn't all it's cracked up to be and he walks away with his family. This is interesting because no one in the family really seemed to be "into" being evil though they were mean and nasty people. It was once they were all faced with the harsh reality of what evil really is that they all had inner turmoil and were seeking a way out of where they'd gotten themselves into. In the end we see Draco, a child who we have seen grow up all mean and nasty, finally peaceful and kind.
In the final movie, Harry has to face off Voldemort alone. Harry realizes that he must die in order to defeat Voldemort because he realizes that one of the horcruxes is him. He goes out to where Voldemort is and offers himself and is killed.
He wakes up in King's Crossing train station that's all bright and white and there is this gross icky creature dying all curled up in a ball. It is the piece of Voldemort's soul which was living in Harry. Dumbledore (the school headmaster who is dead) comes to talk to Harry and encourages him to go back and fight. Harry doesn't need glasses to see here.
So, now, Harry was hit with the death curse (avada cadavara) twice now by Voldemort. Voldemort is triumphant that he's finally killed Harry.
Voldemort has Hagrid carry Harry's "body" to the school where all of the "good" people are fighting together against the "evil" that is coming against the school.
(I'm told of something interesting that is not made known in the movie...but when Harry freely gives his life the entire school is then protected from Voldemort the same way Harry was when his mom gave her life for him.)
In the end obviously, Voldemort is defeated.
My opinion after having watched all 8 movies:
