I think there are two kinds of backstory:
The first kind is the immediate backstory which tells why the character is in their current situation. For example, the immediate backstory can be that the character is looking for the father who abandoned her. This pushes the character into the situations of the story.
The second kind of backstory is the deeper background that leads the character to be the person they are. For example, the character's father abandoned her at birth and her mother died in a terrible fire, leaving her to be raised by family friends. This deeper backstory maybe shown in flashback or perhaps not shown at all, depending on how it affects the character.
The next entry is the backstory for the Mirza family. It's very important because it explains why Tarek acts the way he does. However, some of it will only bore readers while other parts of it will take away from the mystery. I'm sharing it with you because you're part of the creation of this story even though it will take away some of the surprise factor. The next post is friends-only since it is specifically about my story.
My challenge is to give readers enough backstory to understand the characters and make their actions logical for them. I have to do so without boring readings with endless details that slow down the story. Help!