Conflict

Person against Person:  a problem between characters (external)
Person against Self:  a problem within a character's own mind (internal)
Person against Society: A problem between a character and society, school, the law, or some tradition (external)
Person against Nature:  a problem between a character and some element of nature -- a blizzard, a hurricane, a mountain climb, etc. (external)
Person against Fate, the supernatural, God, or gods:  a problem or struggle that appears to be well beyond a character's control (external)