# Blockchain

### layer
* infrastructure (hardware)
* networking (node discovery, information propagation and verification)
* consensus (proof of work, proof of stake)
* data (blocks, transactions)
* application (smart contracts/decentralized applications, if applicable)

# abis
def:the standard way to interact with contracts

## contract
address -> uint160
backerstruct
statstruct

hashtable
mapping(address => projectStruct[]) projectsOf;
mapping(uint => backerStruct[]) backersOf;
mapping(uint => bool) public projectExist;

狀態enumerator:
statusEnum