How to Spot a Counterfeit Bill

This video is a great TED-ed lesson on how to spot counterfeit US bills. There are a lot more things that I would like to know about counterfeiting.

Do you know how paper money started? How do you know whether it will last for a long time? Who guarantees it? Do you know where the word counterfeit comes from (it doesn’t sound English to me). 
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The video mainly discusses the chemistry of how to spot counterfeit bills using a mixture of iodine. The iodine mixture stains the starch in counterfeit bills (when they are made out of paper). 

Here is an Israeli 20 shekel bill that is made out of plastic. Is it easier or harder to counterfeit it? How many countries now use plastic currencty? 

Do you have any idea how other countries approach the counterfeiting problem? 

Is counterfeiting just limited to bills? Is it easy or difficult to counterfeit coin currency as well?

Is it true that it costs more than a penny to manufacture a penny?

People have used money for thousands of years. Do you think that they will continue to use coins and bills five years from now? Ten?

On a lighter note,  there are many bills that are much harder to counterfeit. These bills are real. 

“Aceros cassidix -Vogelpark Walsrode -pair-8a” by Tobias – originally posted to Flickr as Bird Park (“Vogelpark Walsrode”) Germany. Licensed under CC BY-SA 2.0 via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:Aceros_cassidix_-Vogelpark_Walsrode_-pair-8a.jpg#/media/File:Aceros_cassidix_-Vogelpark_Walsrode_-pair-8a.jpg

This Bill looks real. He is standing beside a real Bush. 

On the other hand, they might be look-alikes. How could we tell the difference? Do famous politicians use look-alikes?

If you were an identical twin, would you ever switch places with your twin? 

“Clinton and Bush 2006 (3618970325)” by Tulane Public Relations – Clinton and Bush 2006Uploaded by AlbertHerring. Licensed under CC BY 2.0 via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:Clinton_and_Bush_2006_(3618970325).jpg#/media/File:Clinton_and_Bush_2006_(3618970325).jpg

And we’ll never know for sure whether this guy is for real or not. Will we?