The Federal Reserve’s chief policymaking group, the Federal Open Market Committee, has vast power over the economy through its ability to set monetary policy.

Q: What is the FOMC’s primary role?

A: Its mission is to keep the economy, inflation and employment on a healthy track. When the economy weakens, Fed policymakers cut interest rates or keep them low. The lower interest rates are aimed at promoting increased borrowing and spending by consumers and businesses to spur economic growth. When the economy grows so fast that inflation becomes a threat, Fed policymakers raise rates or keep them high. That makes it costlier for people to get loans and means less borrowing and spending. Economic activity slows and inflation pressures ease.

Q: How does the FOMC move interest rates?

A: Its policymakers decide whether to buy securities from banks. The banks sell those securities to the Fed and receive money from the Fed which they can use to make more loans. That acts to lower the interest that banks charge for those loans. Conversely, if the Fed wants to raise interest rates, it sells Treasury securities to the banks, pulling money out of the financial system and raising the cost for loans.

Q: When does the FOMC announce its rate decisions?

A: Each of the eight meetings each year is followed by a policy statement around 2 p.m. on the second day. After four of each year’s meetings, Bernanke also holds a news conference around 2:30 p.m., as he did Wednesday.

Q: How are the FOMC’s rate decisions approved?

A: By a majority of the 12 voting members. Unlike the Supreme Court, close votes on the FOMC are rare. It might unnerve financial markets if investors felt the Fed chairman couldn’t command widespread support for his policies.