The top class of safe sample identification are barcodes. A barcode is an optical representation of data, which is machine-readable. Machine-readable means readable by a scanner, e.g. a handheld barcode-scanner. We are used to them from e.g. the daily shopping at the supermarket. The label can be limited to the pure barcode or barcode plus plain writing for human reading. The barcode can be printed on adhesive labels or directly printed/ lasered on vessels.