Well, when you make a 3D model, you're basically adding and dragging around hundreds and hundreds of little squares (polygons) to make the shape you want. (The smooth character models you see in movies can have millions of them.) "Low-poly" just means making a model while trying to add as little geometry as you can.



For some reason, though, people usually only list the tri count, which is what you get when you convert the squares into triangles. A tri count of less than 500 is generally the goal for low-poly modeling.