Short version: Controls that help customers narrow product choices by needs, features, size, price or other criteria.
In e-commerce, product filters affects how people find, compare, choose, and buy products. It can sit inside the product page, category structure, cart, checkout, retention flow, or the data that feeds paid and organic channels. The practical question is always whether the customer has enough information and confidence to move forward.
For an online store, small points of confusion can reduce trust or stop a purchase. The strongest use of this term is practical: make the buying journey clearer, reduce friction, and give the customer enough confidence to continue. It should also support measurement, because store improvements only matter if they change real customer behavior.
Related terms: E-commerce category, Navigation, and UX.