Usability Testing Planning is the practice of designing and executing research studies where real users interact with products while researchers observe and measure. You develop research questions, recruit participants matching your target audience, facilitate sessions, and analyze results to identify UX problems and validate design decisions. You plan tests by defining goals ("Can users find the checkout button?"), creating tasks ("Complete a purchase"), recruiting matching participants, and running sessions. You observe how users behave, note where they struggle, and gather insights via observation, think-aloud protocol, or surveys. Results guide design iterations.