A Barcode is a machine-readable representation of numbers and letters, represented by vertical strips of black and white.
In the library system there are normally 2 different types of barcode.
ISBN/EAN
One type is the ISBN/EAN of the book. This is normally on the back of the book and printed as part of the back cover. It is a unique 10-13 digit number (normally starting 978) that identifies the book but not the copy, if you have multiple copies of the same book, they will likely all have the same ISBN. The ISBN is used by publishers, booksellers, libraries and internet retailers for ordering, listing, sales records and stock control purposes. The library system uses it in conjunction with our Discovery Online database to populate a resource's bibliographical data.
Barcode/Accession Number
The other type of barcode used in the library system is most commonly referred to simply as 'the barcode' although some people may know it as an accession number. This is a barcode allocated to the book by you, to identify it as a unique copy from amongst your library stock, no two books in your library should have the same barcode, even multiple copies of the same book. These types of barcodes are also used to identify the borrowers in the library system, again no two borrowers should have the same barcode.
Use
When cataloguing books in your library system you will be asked for the barcode and the ISBN, ensure that you do not scan these in the opposite way round. Once a resource has been catalogued you will not need to scan the ISBN again, all scans in the library system (issuing and returning, searching, stock check) are done with the barcode/accession number.