When may the president invoke executive privilege?

Much of the President's life is public. Their day to day schedule is public. Many of their writings and records are legally owned by the public and subject to the Presidential Records Act. However, in some cases, the president has the power of "executive privilege" to keep certain information confidential in order to protect the deliberations of the executive branch. For example, the president can refuse to share private Oval Office conversations or sensitive memos with Congress or the courts. That being said, executive privilege is not absolute. The president cannot use it to conceal wrongdoing or block investigations into misconduct. If Congress needs the information for oversight or the courts need it for an important trial, executive privilege must yield.