The Presidential Succession Act establishes the line of succession to the presidency of the United States in the event that the President is unable to perform the duties of the office due to death, resignation, removal, or incapacitation. It ensures the continuity of government by specifying the order of officials who are eligible to assume the presidency, starting with the Vice President, followed by the Speaker of the House, the President pro tempore of the Senate, and then the eligible Cabinet members in the order of their department's creation.