It represents inflammatory changes in the fat surrounding an inflamed structure, like in appendicitis or diverticulitis..
What you see are edematous (think of it as water density) changes within a fatty structure, so you will see 'strands' which are slightly hyperdense relative to normal fat.
Not necessarily "inflammatory" stranding. May be simply due to mesenteric edema if it is around loops of bowel or scarring if it is chronic. I like the term "dirty fat" or "fat stranding."
Some feel that the term "inflammatory stranding" is a misnomer.