Blockchain 101

  1. A blockchain is a chain of blocks that contains information or data.
  2. Blockchains are used for the secure transfer of items. The item could vary from money to contracts.
  3. Blockchain does not require a third party
  4. A blockchain is a software protocol (like email)
  5. Blockchain has to have access to the internet
  6. Blockchain is also called meta technology
  7. Blockchain affects other technologies
  8. Once data is stored in a blockchain, it is extremely difficult to change it
  9. Blockchain enables bitcoin, but is not bitcoin
  10. Bitcoin is a digital token
  11. Blockchain is a ledger
  12. A block contains the information stored, which depends on the type of the blockchain
  13. The first block is called a genesis block
  14. A block has a Hash
  15. A Hash is like a unique fingerprint of the block
  16. A Hash is a combination of letters and numbers
  17. If the data is changed in a block, the hash is also changes
  18. Each block contains the data, the hash and the hash of the previous block
  19. The genesis block has no previous hash
  20. If the attacker changes the hash of a block, then the following block is invalid because they do not have the correct hash of the previous block
  21. Changing a single block can make the entire chain invalid
  22. Computers are becoming more and more powerful, so they can decode a whole chain quickly and make it all valid
  23. Proof of work(POW) is used.
  24. POW is a mechanism that slows down the creation of new blocks
  25. A POW is a computational problem that takes a certain effort to solve
  26. It takes some time to solve the POW
  27. if the attacker tampers with a single block, they need to recalculate all the following blocks
  28. P2P is another method used
  29. Everyone on the network has a full copy of the blockchain
  30. Each computer is called a node
  31. When a user creates a new block, the block is sent to every user on the network
  32. Each node needs to verify the block
  33. Once verifies, the block is added
  34. Al the nodes need to create a consensus and reject all blocks that are tempered with
  35. To temper with a blockchain, the attacker needs to do three things
  36. The attacker needs to tamper with all blocks on the chain
  37. The attacker needs to redo the POW for each block
  38. The attacker needs to take control of the majority (more than 50) of the P2P network
  39. There are generally 4 steps of a blockchain
  40. Step 1: A person requests a transaction
  41. Step 2: The request is broadcasted to P2P from nodes
  42. Step 3: The network of nodes validates the transaction
  43. Step 4: Once the transaction is complete, the new block is added
  44. A blockchain is resilient, so if a node is down, there are still many nodes running the system
  45. Blockchain is quick and is faster without a third party
  46. Blockchain is reliable
  47. Blockchain is unchangeable (nearly)
  48. Blockchain is secure
  49. Blockchain does not have a centralized system
  50. There are three general versions of bitcoin
  51. 1.0: the blockchain is used in currency and payments
  52. 2.0: Smart contract is implemented, and small computer programs are within blockchains
  53. The computer programs execute automatic checks
  54. 3.0: A DApp can have frontend Blockchain example code and user interfaces written in any language that can make a call to its backend, like a traditional App
  55. There are also 3 main variants of blockchain
  56. Public: anyone can verify and add a block of transaction
  57. Private: works within a single organization. It allows only specific people to verify and add transaction blocks
  58. Consortium: Only a group of organizations can verify and add transactions. It is also only controlled by pre-authorized nodes

There are not quite 101 points for a basic tutorial, but there are a lot more once you dive deeper. This is meant to give a basic overview of blockchain, so it is not meant to be a detailed guide.

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