Conflict is a disagreement between two or more parts who perceive that they have incompatible concerns. They are natural and inevitable part of people working together, sharing diverse thoughts, concerns, perspectives, and goals. Conflicts may start because of misunderstanding, different views, objectives, values, religions infrequent or ineffective communication and so on…Some of them are small and solvable, some destructive and damaging, growing even into war. Most people have no interest in creating conflict with others. However, at times we feel so exasperated that we focus on our own needs at the expense of others’. And then we find ourselves in conflict.
There are a lot of types of conflicts:
The most important conflicts are:
Intrapersonal conflict occurs within us: when we are at odds with ourselves, when we are frustrated with our goals. Conflict with us very often leads to conflict with others.
Interpersonal conflict occurs between two or more individuals. We might get into a heated debate in a meeting. 
Group conflict occurs between groups: nations, gangs, work areas, etc.
A vivid example of interpersonal and group conflicts can be a story of Romeo and Juliet.
Interpersonal conflict occurs between Romeo, Tybalt, and Merculio. Tybalt kills Merculio, and Romeo, in turn, kills Tybalt.
Group conflict exists between the Capulets and Montagues.
The most interesting and important sort of conflict for us of course is an interpersonal conflict because it is related with us.
If we will appeal to psychology books the most common causes of conflicts are approach and avoidance. To approach is to have a tendency to do something or to move in a direction that will be pleasurable and satisfying. To avoid is to resist doing something, perhaps because it will not be pleasurable or satisfying.
These two categories produce three kinds of conflicts:
Approach-Approach Conflict –both alternatives are incompatible goals.
Approach-Avoidance Conflict - here is a desire both to do something and not to do it.
Avoidance-Avoidance Conflict - here there are two alternatives, both of which may be unpleasant.
Of course there are many views how to divide conflicts and it is impossible to cover all of them
There are two main views to conflicts:
1.Conflicts are bad and should be avoided.
2.Conflict is neither inherently bad nor good but is inevitable and structurally induced.
In my opinion, the second view is more advisable. Conflicts between people are a fact of the life and it’s not necessarily a bad thing. Of course when conflict occurs, the relationship may be weakened but it can be strengthened too. It depends on us, how we will receive and solve these conflicts. We have to talk, express our feelings and listen to other person, try to understand his feelings and together find a solution which will give a satisfaction for both of you.
To sum up, conflicts are not bad things; sometimes they help us to find a decision and solution from the difficult situation. The only one we can do is to act rationally in conflicted situations.
Sources:
http://www.drbalternatives.com/articles/cc2.html
http://www.sonlifeafrica.com/model/conflict.htm
http://www.jlasc.com/conflict.htm