Standardisation

Standardisation is agreeing one consistent way of doing a task or making a product, so it comes out the same every time regardless of who does it or when. It replaces a dozen personal methods with a single best-known method that everyone follows.

It is like every power socket in the country being the same shape, so any appliance simply plugs in and works. Standardisation matters because consistency makes quality predictable, training simpler and improvement possible, since you can only reliably improve a task that is done the same way each time.