Why was WW1 called the war of attrition?

Attrition is the process of reducing something’s strength or effectiveness through sustained attack or pressure. The WWI was called the “war of attrition” because of the events occurred in the trenches along the western front between France and Germany, when both military forces found themselves stuck in defensive positions facing one another along a single front that stretched for hundreds of miles across Europe. Neither army could move against the other except to go head-to-head against one another repeatedly in hopes of gradually weakening the opposing army.