PLU
A PLU is a price look-up code: the short code a till uses to identify a product. On older systems staff typed them; on a modern touchscreen they sit behind the buttons. They matter because they are what reports, stock movements and integrations are keyed on, so a PLU reused for a different product quietly changes the meaning of every historic report about the old one.
In practice
A PLU is the code a till uses to identify an item. On older systems staff typed them; on a modern touchscreen they sit behind the buttons, and they matter mostly because they are what reports, stock movements and integrations are keyed on.
Keeping PLUs stable is one of those small disciplines that pays off a year later. If a code is reused for a different product, every historic report about the old one quietly changes meaning, and nobody notices until they try to compare two Christmases.
When a till is replaced, mapping the old PLUs to the new ones is the unglamorous part of the migration that protects your history.
Also called: price look-up code, product code.