What is ERC721? It is an open standart describing how to build non-fungible tokens on the Ethereum Blockchain. ERC721 tokens are unique and collectable unlike most of the tokens. In addition to that, all ERC721 tokens are different from each other so it is so hard to trade them.
What is Fungible Exactly?
Merriam-webster.com defines it as ‘’being something (such as money or a commodity) of such a nature that one part or quantity may be replaced by another equal part or quantity in paying a debt or settling an account’’.
To exemplify, you have $15 cash in your hand and go to a market to buy chocolate and coke. When you buy it, you give the money to the cashier because the products you bought have a value of dollars in your hand. In other words, when you go to the same market with $15 dollar bill for Nike products, you will not be able to buy anything because they have different characters.
How important are ERC721 tokens?
Most of coins such as Bitcoin or Ethereum and fiat currencies such as USD and Euro are not unique so people can exchange them easily. For example, a 5 dollar bill has a value of 5 dollars or the same value of BTC or ETH. Moreover, such coins (Bitcoin, Ethererum etc…) can be divided into small pieces (0,5 BTC or 0,0005 ETH) although it is impossible to divide the ERC721 tokens.
The most popular project that has been created based on ERC-721 standard is Cryptokitties, a game to buy and sell unique cats. Decentraland and EnjinCoin are the other popular projects using the ERC721 standard.
There are also different areas that use ERC721 tokens such as Realty and Artworks etc. If you are interested in buying or selling the unique coins, you can visit Opensea.io, the biggest market for those type of digital items.