SPDX license identifier

• Introduced in Solidity from Solidity ^0.6.8

Usage §

// SPDX-License-Identifier: MIT
 
pragma solidity ^0.7.5;
 
contract TestContract {
// Some logic
}

List of licenses §

https://spdx.org/licenses/

Refs §

1. Stackoverflow
2. Using SPDX licenses