Normalization vs Denormalization

A product is called "Wireless Mouse" and its name is stored in 40,000 order rows. Marketing renames it.

If the name lives in one place and every order points at it, that rename is one update. If the name was copied into all 40,000 rows to make order pages load faster, that rename is 40,000 updates, and any you miss leave the system disagreeing with itself.

That is the whole trade-off. Normalization stores each fact once. Denormalization deliberately stores it more than once so reads do less work.