In any form of literature, conflict is the struggle, or multiple struggles, at the heart of the author's narrative. Conflict is what moves plot forward and motivates characters to act. Normally, the source of conflict is revealed in the opening passages or chapters of a text, developed until the conflict reaches a point of climax and then resolved at the end of the story.
Man Versus Man
One of the most common forms of conflict in literature is conflict between two individuals. This conflict is generally referred to as "man versus man" or "person versus person." Man versus man conflict sets a protagonist against an antagonist and is the main source of action and movement within a piece of literature. A short story with an excellent example of man versus man conflict is Saki's "The Interlopers." In this story, the two main characters, Georg and Ulrich, appear willing to kill or be killed in a conflict over property rights.
Man Versus Society
Conflicts revolving around the struggles between an individual and the society in which he or she lives are considered "man versus society" or "person versus society" conflicts. These conflicts pit the aims and desires of a primary character against the aims and desires of the society at large. An example of man vs society can be seen in William Golding's "Lord of the Flies." One of the main characters, Piggy, spends the majority of the novel acting in opposition to the prevailing whims of the society that has formed among a group of plane-wrecked boys. Later, the conflict actually turns violent when the entire society of boys turns on its leader, Ralph.
Man Versus Nature
When nature itself is acting as a protagonist or antagonist in literature, the conflict can be described as "man/person versus nature." In these instances, nature may be an actual object -- like a tree, a mountain or a river -- a natural disaster or other naturally occurring element or event. Man versus nature is at the heart of Jack London's short story, "To Build a Fire." In this tale, an unnamed man is racing against time and freezing temperatures to, literally, build a fire, before succumbing to nature and slipping away into permanent sleep. Nature, in this example, wins.
Man Versus Self
Man versus self conflicts manifest when the primary conflict in a story exists between a main character and forces within him/herself. Novels where a character struggles with mental illness or conflicting internal desires are common examples. This kind of conflict is brought to life in Robert Louis Stevenson's, "The Strange Case of Dr. Jekyll and Mr. Hyde." The conflict in this story is made manifest in the actions and consequences brought on by the split personalities of Dr. Henry Jekyll and Edward Hyde, both residing within a single individual.