Hikes fight inflation by making borrowing costlier and cash more attractive; cuts stimulate growth by doing the reverse. What moves markets is the decision relative to expectations and the signal about the path ahead.
One basis point is 0.01%, so a 25-basis-point hike raises the federal-funds-rate by a quarter of a percent.
Example: the fomc hikes 75 basis points when the market expected 50. The 2-year yield jumps, the dxy rallies, and growth stocks fall hardest.
Related: fomc, federal-funds-rate, yield-curve, quantitative-tightening