Product idea research
Customer interviews, surveys, competitor analysis, idea generation. Inspiration + ideation in human- centered design terminology. While this is simpler for client projects, as the main source of truth is the client, things get more complex when dealing with consumer-facing products before reaching product/market fit.
Do people really have this problem? How do they solve it right now? Will they pay for an alternative solution? Will that price cover the customer acquisition cost? And many more interesting questions.