What is executive privilege, and how has it manifested itself in different administrations?

What will be an ideal response?

Executive privilege is one of the barriers to information flow. Though not mentioned in the Constitution, it is now asserted to be one of the powers of the presidency. It basically means presidents can claim immunity from disclosing information and has been used most frequently to keep undisclosed the oral and written communication between the president and White House aides. Examples of such claims for executive privilege can be seen during the Nixon administration’s Watergate affair, Bill Clinton’s appearance before a grand jury investigating his personal conduct in office, and George W. Bush’s testimony before a commission investigating the September 11 attacks.