This is for a solidity tutorial that explains the use of the tx object and gas in solidity

Transaction.sol

// SPDX-License-Identifier: MIT

pragma solidity 0.8.23;

contract TransactionInfo {

    // State variable to store contract balance
    uint256 public contractBalance;
    
    // Variables to store transaction details
    address sender;
    uint256 value;
    
    // Event emitted when Ether is sent to the contract
    event EthSent(
        address indexed sender,
        uint256 value
    );

    // Function to get and return Ether sent to the contract
    function getEthSent() public payable {
        contractBalance = msg.value;
        // Emit an event with the sender and value of Ether sent
        emit EthSent(tx.origin, contractBalance);
    }

    // Function to get the original sender of the transaction
    function getTxOrigin() public view returns (address) {
        return tx.origin;
    }

    // Function to get the gas price of the transaction
    function txGasPrice() public view returns (uint256) {
        return tx.gasprice;
    }

    // Function to get the input data of the transaction
    function txInputData() public pure returns (bytes memory) {
        return msg.data;
    }

    // Function to get the remaining gas limit
    function gasLeft() public view returns (uint256) {
        uint256 gasL = gasleft();
        return gasL;
    }

    // Function to withdraw the contract balance, only accessible by the owner
    function withdraw() external {
        // Only the owner can withdraw the contract balance
        uint256 amount = contractBalance;
        contractBalance = 0;
        payable(tx.origin).transfer(amount);
    }
}