U.S. stocks rallied across the board Wednesday, with the Dow and S&P 500 logging their best one-day gain in 2012, leading “Mad Money” host Jim Cramer to explain just how it happened.

To start, Cramer noted that European Central Bank released a statement that helped to calm investors’ fears over the region’s sovereign debt crisis. The ECB held its key interest rate unchanged at 1 percent, which was largely expected. President Mario Draghi pledged it will act in a timely manner on inflation. He added he expects inflation to stay above 2 percent this year and to ease to between 1 percent and 2 percent next year.