What does it mean when short- and long-term rates are inverted?

When short-term bond yields are higher than long-term bond yields, this is called an inverted yield curve, or an inversion of long- and short-term rates.

Normally, the shorter the maturity, the lower the yield, but it is explained that such inversions can occur when investors expect an economic slowdown and rate cuts. Inversions are often cited as a leading indicator of past recessions, but there have also been cases where no recession followed, so it is hard to judge on that basis alone.