What's the easiest way to print barcodes in Microsoft Office?

The easiest way to print from within Microsoft Office is using a so called barcode font. A barcode font is like a normal font (e.g. Arial or Helvetica) only that it displays barcode elements rather than text or numbers.

Applications are: Mail merge in Word, Catalogs or pricelists in Excel, or reports in Access. Since the barcode Code 39 doesn't require calculating a checksum as most of the other barcode types do, it's particularly suited to be created with a barcode font.