Full explanation
Product Market Fit is the holy grail of early stage startups. It means you have built something that a specific group of people genuinely needs, and they keep using it.
Before PMF, you push. You chase users, you beg for signups, growth feels heavy. After PMF, you pull. Users find you, they stay, they recommend you.
You know you have PMF when stopping the product would make customers genuinely upset.
Concrete example
You launched a tool for freelance accountants. After 6 months, 70% of users come back every week and many ask if you have a referral program. That is PMF.