Lately, more and more countries have been adopting measures to fight counterfeit currency. One of those measures is to create plastic or polymer bills. They are harder to copy, not to mention cleaner and waterproof. They are also environment friendly as their lifespan exceeds that of their paper counterpart.
As of 2016, 17 countries are using polymer currency. These include Brunei, Canada, New Zealand, Papua New Guinea, Romania, Singapore, Kuwait, Vietnam, the United Kingdom, Cape Verde, Chile, The Gambia, Mexico, Nicaragua, Trinidad and Tobago, Republic of Maldives and Nepal.
That being said, if you are in a country where plastic currency is being used, this does not mean your guard should be down when trying to spot counterfeit bills as this video explains it so well: