It uses a technology called rollups, specifically Optimistic rollups, where the transactions are executed off the chain and get bundled into a single transaction before being pushed to the main blockchain. Optimism is a layer 2 scaling solution for ETH, meaning it functions on top of the Ethereum mainnet (L1). PS: I know I just threw a ton of new words at you in the previous section and if any of the above was confusing, don't worry as we'll discuss each one of them in detail.īut before we get our hands dirty, let's take a quick rundown on what Optimism is? What is Optimistic Ethereum? We've already discussed how you can make a fungible token using ERC20↗, but what if you want to create tokens that are not alike at all? What we are BuildingĬryptoKitties really braced the growth and use case of NFTs we see today and in this tutorial, we will walk through creating and deploying an ERC-721 smart contract and minting the token on Optimism Kovan-Testnet using Solidity↗, Hardhat↗ and Pinata↗.īy the end of this tutorial - you'll be able to mint an NFT and display it on Quixotic↗ (an NFT marketplace on Optimism) from your deployed ERC721 contract.

Before the dawn of ERC-721, tokens on blockchain were only fungible, meaning they can be traded or exchanged with another identical one of the same value, much like a dollar bill.

Originally built on the Ethereum blockchain, CryptoKitties was the first non-fungible token (NFT) that allowed the creation of unique digital collectibles as kitties, using the ERC-721 smart contract. Mention NFT revolution and you will most likely stumble upon this project over and over again: CryptoKitties.

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