# What is Smart Contract

:::info
NCKU GDSC Smart Contact study group ( Week 1 )
:::

[reference : 「在 2022 年，我們該如何寫智能合約」 on iThome ](https://ithelp.ithome.com.tw/users/20083367/ironman/5136)

## D1 - D10
Introduction to blockchain ( Ethereum )

### D1 : What is `block` and `chain`

- Feature :
- can't by modify
- decentralized
- Block :
- Transaction :
A block contains many transaction . Transaction can be classcify by `Create` and `Execute` .
- Action :
- Create :
Deployment of Smart Contract
- Execute :
- Recieving Ether
- Interact with Samrt Contract
- Properties :
- Recipient :
- Address ( The address of recipient )
- Value
- Nonce :
- Counter
- Signature :
Sign by private key of sender
- Value :
amount of Ether
- data
- The most important , send data to contract
- Gas Limit
- maxPriorityFeePerGas
- maxFeePerGas
- Chain :
- The order of Transaction
- if the
- Connecting the block

- Gas :
- Why :
Every transaction require computation resources . Base on `Fee-For-Service System` , the sender account has to pay the fee.
- Gas ? :
the Unit that describe computation resources ( describe the any operation cost running on `EVM (Ethereum Virtual Machine) ` )
- GasLimit :
The max amount of gas that sender can pay in this transaction . ( Note that , if the GasLimit < the gas that the transaction needs , the transaction will fail( `revert` ) )

- Fee :
- BaseFee :
- Prioroty Fee :
- Max Fee:
- Max Fee = Fee per Gas
- Fee per Gas = BaseFee + Priority Fee
- The transaction tool will calculate itself
- Total Fee :
- Total Fee = Max Fee * Used Gas

- Account :
- Balance
- Call
- can interact with Smart Contract
- EOA ( Externally-owned account ) :
- just like our personal acount
- Balance
- Nonce
- Is able to :
- recive/sende Ether :
- interact with Contract Account
- Contract Account :
- Balance
- Nonce
- Codehash
- storageRoot / storageHash
- Is able to :
- recive/send Ether :
- will only start by EOA

- NetWork :
- Chain ID :
- equivalent to Network ID
- MainNet
- TestNet :
- Goerli
- Sepolia

- Consensus :
- Miner / Validator :

- PoW :
- PoS :

- Intro to Ethereum Stack :

- EIP ( Ethereum Improvement Proposals ) :
- document that
- ERC

- ERC ( Ethereum Request for Comments )
- software interface standard
- ERC-20
- Properties :
- name
- symbol ( optional )
- decimals
- Smaller Unit
- no float/double in solidity
- totalSupply
- balanceOf
- balance of an address
- transfer
- transferFrom
- approve
- allowance
- Events :
- Transfer
- Approval
- Eg :
- Stable Current : every coin has same value
- BTC , ETH , USDT
- Stock
- ERC-721
- Non Fungible Token
- Properites & Events :
- unique TokenID
- Metadata Extension :
- encode json by base64
- enumeration extension :
- for other functionalties
- ERC-721A :
- a new way to store tokenId and address
- don't store the same owner name ( if continue )
- ERC-721R :
- with time limit

- ERC-1155 :
- ERC-1155 = ERC-20 + ERC-721
- ERC-20 :
- tokenId = 0 , amount = N
- ERC-721:
- tokenID = 1 , amount = 1 ; tokenID = 2 , amount = 1 ; ...

- Example of Smart Contract