They are pre-cut fabric pieces usually used in quilting. Most are cotton and are usually measured at 18x22 inches. They are a quarter of a yard but measured 18x22 rather than 9x44 (44"wide fabric cut into a quarter of a yard). They are sometimes sold in bundles of 8 although most are sold by each piece... prices vary but usually piece items are around $1.99 each... sometimes bundles can be purchased much cheaper. Prewashing a fat quarter results in less raveling of raw edges too. HOPE this helped ...