Conflict in a story is any form of opposition or difficulty encountered by the main character. Conflict is an essential piece of a story, as it makes a plot. Without conflict, there is no story to tell.
Conflict comes in many shapes and sizes. It can be internal or external with either the character fighting himself from within or outside forces acting against the character. There can be many struggles faced in a tale or one central conflict.
There are four different kinds of conflict: man versus man, man versus circumstances, man versus society and man versus himself. Each kind of conflict brings with it its own struggles and may intertwine with other kinds of conflict.