The kind of friction and frustration that shows up repeatedly in real lives and that people have accepted because nobody has fixed it yet.
Notice is not market research in the traditional sense. It is a practice of attention. It means being close enough to real customers to hear what they actually say, not what you hoped they would say. Resisting the pull of your own assumptions long enough to find out what is true.
Most businesses do not fail because the idea was bad. They fail because the idea was built for an imagined customer rather than a real one. Notice is the habit that protects you from that. The best business ideas rarely appear through structured innovation exercises. They appear when you are close to real people dealing with real frustrations.
Look for workarounds. When someone builds a spreadsheet or creates a manual process to deal with something that should not require that effort, they are demonstrating that the demand is real and the current solutions are inadequate. Workarounds are market signals.