Reverse repurchase agreements involve the sale by the Fed of securities from its portfolio with an agreement to buy the securities back at a slightly higher price at a later date.

WSJ: Bernanke Op-ed in WSJ: The Fed��s Exit Strategy

First, the Federal Reserve could drain bank reserves and reduce the excess liquidity at other institutions by arranging large-scale reverse repurchase agreements with financial market participants, including banks, government-sponsored enterprises and other institutions.

WSJ: Bernanke Op-ed in WSJ: The Fed��s Exit Strategy

The usual approach is to conduct reverse-repurchase agreements, borrowing from one of its 16 primary dealers for short periods of time in order to finance the assets on its balance-sheet.

ECONOMIST: Central banks' exit strategies