There is controversy about the relative quality of CD sound and LP sound when the latter is heard under the very best conditions (see Analog vs. digital sound argument). It is notable, however, that one technical advantage with vinyl compared to the optical CD is that if correctly handled and stored, the vinyl record will be playable for decades and possibly centuries, which is longer than some versions of the optical CD. For vinyl records to be playable for years to come, they need to be handled with care and stored properly. Guidelines for proper vinyl storage include not stacking records on top of each other, avoiding heat or direct sunlight and placing them in a temperature controlled area which will help prevent vinyl records from warping and scratching. Collectors store their records in a variety of boxes, cubes, shelves and racks.