What is the type of `this` object in solidity - solidity

Question

In the following claimPayment function that is used to claim a payment made earlier to this contract, the line bytes32 message = prefixed(keccak256(abi.encodePacked(msg.sender, amount, nonce, this))); has this as part of the signed message. This makes me wonder what is this and what the type of this is. If I'm returning this in a function, what type is used for it? Thanks.
function claimPayment(uint256 amount, uint256 nonce, bytes memory signature) public {
require(!usedNonces[nonce]);
usedNonces[nonce] = true;
// this recreates the message that was signed on the client
bytes32 message = prefixed(keccak256(abi.encodePacked(msg.sender, amount, nonce, this)));
require(recoverSigner(message, signature) == owner);
payable(msg.sender).transfer(amount);
}

Answer 1

this is a pointer to the current class instance, as in many other programming languages. You can for example point to public methods:
pragma solidity ^0.8.0;
contract MyContract {
function foo() external {
this.bar();
}
function bar() public {
}
}
When this is typecasted, it takes a form of the address, where the current instance is deployed.
pragma solidity ^0.8.0;
contract MyContract {
function foo() external view returns (bytes memory) {
return abi.encodePacked(this);
}
function bar() external view returns (address) {
return address(this);
}
}