What is a “war of attrition” and how does this phrase apply to WWI?

War of attrition is a style of warfare fought where one side tries to “wear down” the other side, be that mentally, physically or casualty wise.

This is often associated with World War 1 because it was the most common style of fighting that occurred, mainly in the form of trench warfare, where one side would launch attack after attack to try and wear the other side down.

Hope this helps!