Although smart contracts have been around for quite a while, their concept still remains somewhat of a mindbender for the average user. This series of articles aims to shed some light on the purpose and working principles of the selected smart contracts supported by Smartz platform thus providing you with a simple explanation in relation to each of them. Today’s article is dedicated to the ERC-721 token, a non-fungible token applied in crafting blockchain-based collectibles.

As with the previously discussed ERC-20 token, the acronym «ERC-721» stands for «Ethereum request for comment 721», a token standard which was introduced in late 2017 and gained popularity thanks to the huge success of CryptoKitties, a collectible card game which finally allowed digital community to grow and trade virtual pets, each being one-of-a-kind. Though the standard itself was developed before the actual release of CryptoKitties, it became associated with this game; similar projects like CryptoPuppies (who’d have thought) and CryptoPunks would follow. The nature of these games provides the best explanation of the ERC-721 token, which is basically a digital representation of a non-fungible asset — an asset with unique features whose value can’t be measured objectively and depends primarily on one’s aesthetic opinion.

The non-fungibility of the ERC-721 token allows to distinguish between it and the ERC-20 token: each ERC-20 token has the same value as others (just like a one dollar bill has the same value as another one dollar bill); each ERC-721 token, on the other hand, is unique in terms of its design and value, which is why one can’t launch an ICO on the ERC-721 as opposed to the ERC-20. In this sense ERC-20 tokens can be thought of as a currency, whereas ERC-721 tokens represent things. Another major difference is that unlike ERC-20, ERC-721 tokens can only be traded in whole, since it’s impossible to transfer or sell half of a digital asset — one can’t transfer half a digital kitty.

It should be pointed out that the scope of application of the ERC-721 can not be reduced solely to the emulation of digital collectibles. Indeed, this standard can be used in digitizing different unique assets like real estate, intellectual property, works of art — the latter being a particularly promising field for ERC-721, given the fact that it will allow to track the authenticity of an artwork, it’s origin, the copyright holder, etc. By extension, this standard can be applied to the proof of ownership and authenticity of any valuable digital or physical asset exposed to forgery, be it a diamond or a rare painting.

From the technical point of view the ERC-721 standard inherits many features of the ERC-20: for instance, certain functions of the ERC-721 (token name, token symbol, total supply, token balance, etc.) comply with the ERC-20, which makes working with the ERC-721 more predictable for those who have already dealt with ERC-20. With this in mind, the specific nature of the ERC-721 token implies the introduction of many new functions, most notably functions related to the token metadata which allow to find more information about the token. The creation of an ERC-721 token is also different from ERC-20: when it comes to ERC-721, one can’t create a bunch of tokens as with ERC-20, but rather has to create each token individually since each token is unique.

The deployment of an ERC-721 token on the Smartz platform is actually not that big of a deal even for a non-tech savvy person: if it is the first smart-contract you’re working with, you can use a simple step-by-step guide on how to deploy relatively similar smart contracts. You can also visit this page to learn more about the functions for ERC-721 token and the details of its deployment in general. The whole process can be best described as intuitive, since both mentioned guides are self-explanatory.

Also we prepared a simple video about deploying ERC721 token on Smartz platform. More info on the supported smart contracts will follow.

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