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2. Intermediate Course

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  1. 1. Ethereum 2.0 - What is it? 
  2. 2. What is cryptocurrency burning?
  3. 3. How to create your own cryptocurrency? 
  4. 4. Blockchain Oracle - what are oracles? 
  5. 5. How to make money with NFT?
  6. 6. What is an ERC20 token and how is it created?
  7. 7. The Metaverse – a new virtual world
  8. 8. Metaverse – TOP 15 virtual reality projects
  9. 9. Technical analysis – is it worth using?
  10. 10. What are DeFi liquidity pools?
  11. 11. Second layer (layer 2) - what is it? 
  12. 12. What are wrapped tokens 
  13. 13. What is the Lightning Network, and how does it work?
  14. 14. What are security tokens?
  15. 15. What is Play-to-Earn (P2E) and how does it work?
  16. 16. What are Social Tokens? 
  17. 17. Examples of the use of WEB3 on the blockchain
  18. 18. What is Web5? 
  19. 19. Ethereum London Hard Fork - what is it ? 
  20. 20. Segregated Witness - what is Segwit Bitcoin all about?
  21. 21. Polkadot - Decentralized blockchain and DOT cryptocurrency
  22. 22. Polkadot Parachain - Next-generation blockchain
  23. 23. Trading order types: stop loss, trailing stop loss, LIMIT
  24. 24. Set up of Stop Loss and Take Profit orders
  25. 25. What are Decentralized Cryptocurrency DEX Exchanges?
  26. 26. What is Curve Finance?
  27. 27. What is GameFi and how does it work?
  28. 28. Non-fungible tokens and NFT exchanges
  29. 29. Cryptocurrency steps - What is move to earn M2E?
  30. 30. What is Proof of Reserves (PoR)? How does it work?
  31. 31. Interoperability in the world of cryptocurrencies and blockchain
  32. 32. Blockchain and its layers - What is layer three in Blockchain (L3)?
  33. 33. What is Layer 0 in Blockchain technology?
  34. 34. What is layer 1 in Blockchain?
  35. 35. What is MakerDAO and DAI Stablecoin?
  36. 36. What is Blockchain sharding?
  37. 37. What is the NFT licence fee?
  38. 38. What is the SubDAO protocol, and how does it work?
  39. 39. The main differences between static NFT and dynamic NFT
  40. 40. What is minting an NFT?
  41. 41. Mainnet versus Testnet on the Blockchain. The complete guide!
  42. 42. What are NFT Ordinals? A guide to Bitcoin NFT.
  43. 43. Market Cap versus Fully Diluted Market Cap - the most important differences you should know!
  44. 44. MINA Protocol: the lightest blockchain in the world!
  45. 45. NFT Gas Fee - what is it? How can you reduce your gas fee?
  46. 46. Liquidity Provider Tokens (LPs). What are they, and why are they so important?
  47. 47. What is KnowOrigin NFT, and how does it work?
  48. 48. What is decentralized social media?
  49. 49. What is the Ethereum Name Service (ENS) and how does it work?
  50. 50. Arbitrum: Ethereum scaling solution - everything you need to know
  51. 51. Ethereum ERC-4337 - what is it and how does this standard work?
  52. 52. Sustainable Blockchain - Proof of Useful Work & Flux
  53. 53. Ethereum Proof-of-Stake (PoS) - what should you know?
  54. 54. Atomic Swap: What is an atomic swap, and how does it work with cryptocurrencies?
  55. 55. What Is Cryptocurrency Vesting? What Are Its Advantages?
  56. 56. What Is the Metaplex Candy Machine Protocol? How Does It Work?
  57. 57. What Is the BNB Greenfield Ecosystem?
  58. 58. Real Yield in DeFi - what is this trend? What does it consist of?
  59. 59. What Is Slashing in Cryptocurrencies?
  60. 60. How to Create Your Own Decentralized Autonomous Organization (DAO)?
  61. 61. The ERC-721X VS ERC-721 Standard – Key Differences!
  62. 62. Royalties – What Are They? How Does This Type of Licensing Fee Work?
  63. 63. Polygon 2.0 - the value layer for the Internet
  64. 64. ERC-6551 - the new NFT standard. What does it bring to the non-exchangeable token sector?
  65. 65. What is TradFi? The importance for cryptocurrencies!
  66. 66. What is the Real World Asset (RWA) trend in cryptocurrencies? Explanation and examples!
  67. 67. Pyth Network: a powerful oracle harnessing the power of Solana!
  68. 68. Vampire Attacks in Decentralized Finance (DeFi): Explanation and Examples
  69. 69. What are stables in the world of cryptocurrencies?
  70. 70. What Is Binance Oracle?
  71. 71. What is NFT Lending all about? An innovative solution in the world of cryptocurrencies!
  72. 72. Shibarium: A new era in the Shiba Inu ecosystem?
  73. 73. What is an ETF? How will an exchange-traded fund on bitcoin work?
  74. 74. Symmetric and asymmetric encryption - key cryptography techniques!
  75. 75. Cosmos SDK: Building the Blockchain Ecosystem
  76. 76. DAO Investment: A revolution in the world of finance and investment
  77. 77. What is cross-chain interoperability in Blockchain technology?
  78. 78. Blockchain trilemma - explanation of the problem. What is the impact on cryptocurrency payments?
  79. 79. Hedging in cryptocurrencies - great portfolio protection against risk!
Lesson 61 of 79
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61. The ERC-721X VS ERC-721 Standard – Key Differences!

Tokens are designed within the blockchain. Each of them meets certain standards. Such a defined standard allows us to certify a given NFT and its authentication.

Every non-fungible token is generated through a smart contract, making it distinguishable and uniquely identifiable. The commonly used standard for this purpose is ERC-721.

More recently, because during the Bitcoin Ordinals boom, Solidity’s leading developer CyberKongz, OwlofMoistness developed an enhancement to this widely used standard. ERC-721X, as it is referred to, adds many beneficial layers of security to our NFTs. Let’s get to know it better and take a look at the key differences that define these two standards!

ERC – What Is It Exactly?

ERC, or “Ethereum Request for Comments” – this is a token standard that implements an API for smart contract tokens. It provides basic functions for these NFTs, such as:

  • Transferring tokens from one account to another.
  • Obtaining account balance.
  • Obtaining information about the total supply of tokens available on the network.
  • Confirming transactions.

The most common standard that we are familiar with is ERC-20. It is responsible for fungible NFTs. In practice, this means that each token is exactly the same in type and value as another token. For example: one ERC-20 token works similarly to 1 ETH.

ERC-721 – What Does This Standard Mean?

It is definitely an improvement for ERC-20. A token with this standard is unique, but at the same time can have a different value than a token from the same contract. How is this possible?

You need to know that all NFT tokens have a variable Unit256 function called TokenId. For each ERC-721 standard token, the combination of Contract Address, Unit256 and TokenId can be different. As a result, the TokenId function can use the input data and show us a picture of something really cool!

ERC-721 was invented by William Entriken, Dieter Shirley, Jacob Evans and Nastassia Sachs in January 2018.

The ERC-721X Standard: A New Proposal for Non-Fungible Tokens!

The new token standard is something like 2FA on-chain. There are many dangers lurking in the cryptocurrency sector. Scammers are just waiting for us to stumble and make a mistake. Hence the idea of ERC-721X, which is a token to protect NFT holders. ERC-721X offers two-factor authentication by designating the owner’s second wallet as a “gatekeeper,” ensuring NFT transfers require proper authorization.

How Does ERC-721X Work…?

This standard consists of two layers: locking and guarding.

The locking function is linked to the ERC-721 standard. When you lock your NFT, you use the lock registry. This is a system that combines with ERC-721 in its operation, and requires a small amount of gas. The function allows you to lock and unlock your resources. We cannot move our resources until they are removed from the lock registry.

The lock registry itself was created with parallel staking capabilities in mind. Assets staked this way can be used on multiple systems without losing ownership.

The second option of the ERC-721X standard is the guarding function. Instead of a wallet holding an NFT and blocking tokens, a wallet holding NFT data assigns a second wallet as a protection wallet. This is called the “Guardian” wallet. Such a wallet can then block assets in the wallet, and is also responsible for approving the tokens in question for transfer, seemingly creating a 2FA of the chain. The guardian wallet must be a cold wallet to ensure the highest level of security.

What Problems Does ERC-721X Solve?

First of all, the issue of security. We use hot wallets on a daily basis, because let’s be honest – they are convenient to use. However, with such convenience, come many dangers.

The guardian contract secures hot wallets. It allows us to safeguard our assets by adding another layer of protection, in the form of a second hardware wallet. With this standard, scams will be more difficult to carry out. Email attacks, social engineering scams, seed phrase scams – none of these methods will work if they are blocked with a second wallet.

Thanks to ERC-721X, the number of hacking attacks will be drastically reduced, saving hundreds of thousands, if not millions in NFT value for users!


The new standard will make the Web3 community feel even safer. The technology is a step forward to enhance the security of non-fungible tokens. Other projects are increasingly eager to adopt the ERC-721X standard in their collections.

ERC-721X was created to add a layer of security for NFT holders. It allows users to participate in staking with a lock registry and designate a “Guardian” for two-factor authentication (2FA).

Complete today’s lesson!

  1. What is an NFT? [BEGINNER LEVEL]
  2. What is an ERC-20 token and how is it created? [INTERMEDIATE LEVEL]
  3. How to create your own NFT. [MASTER LEVEL]