Product-market fit is about retention.

Your venture has unlocked a strong product-market fit when it has strong retention.

How do you get retention?

Retention = Utility + UX + User Returns

Utility = Product gets the job done for users to solve their problems

UX = Product is easy and delightful to use paired with eye-pleasing UI.

User Returns = Users return frequently and/or at a triggered event to get utility facilitated by UX

When you build a product that your market loves to use frequently and willing pay to solve their problems - you have strong retention.

Strong retention = strong product-market fit