In layman's words:

• Surrogates should be hidden from the user.
• If there's not a business candidate key to show to the user, then the auto generated integer column you use a PK is not a surrogate key ( surrogate means substitute ) but a natural key that happens to be auto generated. In that case it must be shown.

In layman's words:

• Surrogates should be hidden from the user.
• You should expose some other business candidate key to the user.
• If no other candidate key exist you should show the PK. But in this case the PK is not considered a surrogate since it's not a substitute for other column.

In layman's words:

• Surrogates should be hidden from the user.
• If there's not a business candidate key to show to the user, then the auto generated integer column you use a PK is not a surrogate key ( surrogate means substitute ) but a natural key that happens to be auto generated.

In layman's words:

• Surrogates should be hidden from the user.
• If there's not a business candidate key to show to the user, then the auto generated integer column you use a PK is not a surrogate key ( surrogate means substitute ) but a natural key that happens to be auto generated. In that case it must be shown.