An internal conflict is the struggle occurring within a character's mind. Things such as the character views for, but can't quite reach. As opposed to external conflict, in which a character is grappling some force outside of him or herself, such as wars or a chain breaking off a bike, or not being able to get past a road block. The dilemma posed by an internal conflict is usually some ethical or emotional question. Indicators of internal conflict would be a character's hesitation or self-posing questions like "what was it I did wrong?". An internal conflict can also be a decision-making issue.
The term "internal conflict" is also widely used to describe a military conflict within a nation, such as a civil war. An internal conflict is a non-international conflict. It can be because of political, economic or religious causes.