The first paper currency issued by the Department of the Treasury were Demand Notes Series 1861. The original "Greenback" was created during the Lincoln Administration. It is considered by some to be a "fiat currency" because its value is not connected to gold or silver. The first series Greenback is exchangeable for a government bond that pays 6 per cent interest per annum. The Greenback came with a red seal.

 

The above image is a counterfeit 1862 note. It was printed on legitimate paper, but has no red seal. Therefore, it is counterfeit.

1963 five dollar note

During 1963, two different five dollar notes were manufactured. One is a red seal U.S. note that the U.S. government used to pay its debt. The second note (bottom) is a Federal Reserve $5 dollar note that is used to put the U.S. government into debt. Eventually, the red seal notes that came in different denominations ($1, $2, $5, $20, etc.) were completely discontinued. Currently, only Federal Reserve notes are used for our paper currency. The rules for the usage of Federal Reserve notes also applies to digital money (money that is not currency.) In other words, it is assumed that an electonic dollar is a Federal Reserve note as opposed to a red seal note or silver certificate. (An additional note: it is interesting to see Lincoln's visage on this 1963 red seal. Kennedy was assasinated in 1963. Some have speculated that Lincoln was assassinated by international bankers...Kennedy too, although there seems to be no proof of either claim.