Ethereum Smart Contract - HelloWorld example

HelloWorld.sol

// SPDX-License-Identifier: MIT
pragma solidity 0.8.20;

// This defines a contract named “HelloWorld”.
//
// A contract is a collection of functions and data (its state). 
// Once deployed, a contract will exist at an address on the Ethereum blockchain.
contract HelloWorld {

    // This is a public function that returns the string “Hello World”. 
    // It is declared pure because it doesn’t read or modify the blockchain state.
    function sayHelloWorld() public pure returns (string memory) {
        return "Hello World";
    }
}