Single line (//) comments and multi-line(/* ... */) comments are used, although apart from this there is another type of comment style called Natspec Comment, which is also possible; in this type of comment, we either use /// or /** ... */, and they are to be used only earlier function declaration or statements.

Natspec is short for natural specification; these comments as per the latest solidity version (0.4.24) do not apply to variables, even if the variables are public. Here is a small code snippet with an example of such these types of comments:

pragma solidity ^0.4.19;

/// @title A simulator for Batman, Gotham's Hero
/// @author DC-man
/// @notice You can use this contract for only the most basic simulation
/// @dev All function calls are currently implement without side effects
contract Batman {
 /// @author Samanyu Chopra
 /// @notice Determine if Bugs will accept `(_weapons)` to kill
 /// @dev String comparison may be inefficient
 /// @param _weapons The name weapons to save in the repo (English)
 /// @return true if Batman will keep it, false otherwise
 function doesKeep(string _weapons) external pure returns (bool) {
 return keccak256(_weapons) == keccak256("Shotgun");
 }
}