Line memory is a fishing line’s propensity to retain the shape of whatever it was spooled on.  For example. When you pull a fishing line from a spool it will tend to form into loops. This is line memory. Hard lines with strong abrasion resistance are the most likely to have strong line memory. Thicker, heavier lines are more likely to have a strong memory. Lines that retain shapes are more inclined to tangle and generally have poor casting performance. To avoid memory, look for fishing lines that feel soft and supple. Most fishing lines with low memory as a feature will list this feature in the advertising. Memory is usually only an issue with mono and fluoro lines. Top-quality fishing lines have low memory and are recommended.