Conflict, as far as stories go, occurs when the needs or wants of a character are either being thwarted by the needs and wants of another character or by an impersonal force, such as nature. Lord of the Flies is a book that is filled with conflicts, enough so that you could pick out more than five. I'll try to mention some of the bigger ones, though.
- Man versus nature -- The boys are in conflict with the environment in that they are stuck on an island with limited fresh water, food, and no shelter. They are at the mercy of both the sun and the weather. Think about how the little 'uns keep getting sick because they eat the unripe berries, or how a tiny scrape could lead to a deadly infection for lack of medical supplies.
- Man versus man -- By the end of the story, you litterally have some characters fighting for survival against others, such as piggy getting nailed with the big rock.
- Man versus man -- There is a struggle for leadership between Ralph and Jack.
- Man versus nature -- There is a conflict shown in the hunting of the "monster," which turns out to be a pig.
- Man versus man -- The reason they are stranded on the island in the first place is because, it would seem, their plane was shot down as a result of fighting going on "out there."
- Man versus himself -- The characters, especially the young ones, are very afraid of the Beast.
- Man versus himself -- Roger must come to terms with his hallucinations regarding the pig's head.
There are many more you could come up with, but these are a pretty good start.