The term “line of sight” is used to refer to auto-ID technologies that require a reading device in order to “see” a data carrier—that is, for there to be no physical obstruction between the two. Bar codes, for instance, require that a scanner be able to emit a laser that can read a bar code (data carrier) without obstruction. If the bar code faces the wrong way, or if it is torn or dirty, it will likley not be readable.
One advantage RFID offers is that it does not require line of sight. You can embed a transponder (the data carrier) in a box, label or product itself, and the energy from the reader will pass through many materials, and the transponder will be able to respond with the information it carries.
Keep in mind that this is not the only difference between RFID and bar codes. RFID can also carry a greater amount of data over longer distances, and often does not require a human being to be involved in the data-collection process. Items can be picked up by forklifts and carried as normal, and systems can be set up to automatically scan the RFID tags on objects. This is much more difficult to accomplish with bar codes.
—Mark Roberti, Editor, RFID Journal
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