The trend over time.
What 10Y-3M Yield Curve measures.
The difference between the 10-year and 3-month Treasury yields, in percentage points, published daily by the Federal Reserve (via FRED series T10Y3M).
A negative value means short rates are above long rates, an inversion. Inversions of this spread have preceded most U.S. recessions in recent decades, usually by several months to over a year, although the timing is irregular and it is not a perfect signal.
Why it matters.
When long-term bond yields trade much higher than short-term ones, it suggests investors expect steady economic growth, which typically keeps borrowing costs reasonable for mortgages and business loans.