The Secretary to the President is a long-standing position in the United States government, known by many different titles during its history.
In the 19th- and early 20th-century it was a White House position that carried out all the tasks now spread throughout the modern White House Office. The Secretary would act as a buffer between the president and the public, keeping the president's schedules and appointments, managing his correspondence, managing the staff, communicating to the press as well as being a close aide and advisor to the president in a manner that often required great skill and discretion. In terms of rank it was a precursor to the modern White House Chief of Staff until the creation of that position in 1946.
During the mid 20th century, the position became known as the "appointments secretary", the person who was the guardian of the president's time. He had the responsibility of acting as "gatekeeper" and decided who got to meet with him.
The modern-day position of the president's secretary is fulfilled by a administrative assistant or personal assistant in the White House Office Oval Office Operations department who has a desk directly outside the Oval Office.