Gayle Laakmann

CLRS' famous algorithms textbook He could describe in detail the myriad

All products and features start with research and planning. This is the time when the PM is starting to think about what to build next. The next idea may come from a customer request, competitive analysis, new technology, user research, the sales or marketing teams, brainstorming, or the big vision for the product.

Goals
Use Cases
Requirements
Wireframes
Bullet points describing every possible state of the feature
Internationalization
Security