Simplify the following text for a Grade 10 native English-speaking person.
Original: The International Standard Book Number ( ISBN ) is a unique numeric commercial book identifier based upon the 9-digit Standard Book Numbering ( SBN ) code created by Gordon Foster , now Emeritus Professor of Statistics at Trinity College , Dublin , for the booksellers and stationers W.H. Smith and others in 1966 .
Simplified: The International Standard Book Number , ISBN , is a unique commercial book identifier barcode . The ISBN system was created in the United Kingdom , in 1966 , by the booksellers and stationers W.H. Smith .