Three parts into this series, and if you'd asked me to define the word sitting underneath every single hook I'd taught you, I'm not sure I could have done it cleanly. That's not false modesty. Go back and read Parts 1 through 3. I used the word "Action" constantly. I never once stopped to say what one actually is. Part 1 opened with three state variables I'd hand-rolled for years, a result, a pending flag, an error, and showed how useActionState collapses all three into one call. Part 2 ...