MVP (Minimum Viable Product)
The smallest version of your product that delivers real value, built to test whether people actually want it.
An MVP is the leanest thing you can ship that still solves a real problem for real users. The point isn't to be unfinished, it's to learn fast: you build only enough to test your core bet, put it in front of people, and let their behavior tell you whether to keep going.
For a solo founder the MVP is a discipline against the biggest failure mode, spending months building something nobody wanted. Every feature you cut is time you get back to validate the idea sooner. The goal is evidence, not polish.
The trap is over-building "just one more thing" before launch. You often don't need much code at all to test demand. Launch an MVP without code shows how to get a testable version live in a single sitting.