Bar code is a pattern of bars and spaces which represent numbers, letters or characters. Code 39, for instance, has a unique pattern. Code 3 of 9, as it is sometimes called, derives its name from the way in which the pattern is created.
Bar codes are accurate.
They eliminate manual data entry errors. Research has shown that the error rate due to bar code misreads is less than one thousandth of one percent. Tests have shown that bar coded information had a throughput accuracy rate of 1 error in 10,000,000 characters. Compare that to keyboard entry error rates of 1 error in 100 characters. Bar codes speed data entry.