Does smart contract mean coin?

Question

I am new in blockchain tech. In all videos or documentation, people write tons of things about blockchain and smart contract and I think no one knows exactly what the smart contract means. Because they are not explaining it in an easy way.

When I create a smart contract in Solidity and publish in blockchain, am I creating a new coin in blockchain environment?

If so, people could see my coin and invest in it. But I am not creating my smart contract like Bitcoin or Shibacoin . I want to create it just for storing for example people's todo app data .

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And also a bonus question:

I am creating a todo app in Solidity and publishing it publicly in blockchain. I published my app in Android Studio so users can add their todo list data.

Data is stored in, I think, every node distributed. Meaning everybody's computer who has blockchain technology stores todo app data. If someone closes his/her computer, this means that I can't see some of this data in his/here computer?

The reasoning being that, if people have todo app data of other people in their computer, other people's data cannot be hacked?

Answer 1

If your contract follows a token standard (eg ERC-20 ), then it effectively represents a token. In other cases, it does not represent any token.

So if you create a ToDo app contract without implementing the token standard functions, then it's not a token.

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Solidity code effectively runs in EVM (Ethereum Virtual Machine), which is part of a distributed system. By design, every node of the.network holds the same copy of all data across the system.

Applied to your example: All nodes of the.network hold all ToDo notes of all users.

You can distinguish the data on the application level:

struct Note {
    uint datetime;
    bool done;
    string note;
}

mapping (address => Note[]) notesPerUser;

But if the nature of the data is not meant to be readable by anyone, you might want to use a private EVM.network (eg Hyperledger) instead of a public one (eg Ethereum). Or a completely different architecture (eg a centralized database instead of a smart contract).