Before 2008 the Fed announced a single target and hit it by adding or draining reserves. In an ample-reserves world it announces a range instead and steers the market rate inside it using administered rates: iorb near the top and the overnight-reverse-repo-facility rate at the bottom.
Everything at the front of the curve is priced off the expected path of this range. fed-funds-futures and ois quote it directly, and a "hike" or a "cut" means moving the whole band by 25 basis points, occasionally 50 or 75.
Example: the range is 4.25 to 4.50%, IORB is 4.40%, the ON RRP rate is 4.25%, and effr prints 4.33%. A 25 basis point rate-cut moves the band to 4.00 to 4.25% and EFFR should settle near 4.08%.
Related: federal-reserve, fomc, effr, iorb, rate-cut