Testing one user early in a project is better than testing 50 near the end

design How things should be made and judged: what makes a design good, who should do the designing, and what an interface is for.

product management What a product manager is for, who decides what gets built, and what happens to that job once delivery is cheap.

software quality Whether a program is any good and how anyone would know: tests, review, debt, and what a suite cannot cover.