Product is truth. Demand is goodness. Trend is beauty.
A company that lives is a company that solves the trinity simultaneously. Product is the truth of execution — what actually works in the world. Demand is the goodness of fit — whether what you make serves what people need. Trend is the beauty of timing — whether you are arriving at a future that wants to be born. Get one of these right and you have a hobby. Get two right and you have a startup. Get three right and you have a company.
The artifact that survives contact with reality. Product is where the messy truth of users, latency, edge cases, and physics is converted into something that ships. No amount of strategy can repair a product that does not work.
The match between what you make and what people will rearrange their lives for. The goodness axis of business is brutal — it does not care how clever your product is if no one needs it.
Riding a wave that already exists is a thousand times stronger than pushing one that does not. Trend is aesthetic perception applied to time — the felt sense of what is about to become inevitable.
First time the triad scales: real product, vast demand, perfect trend (Renaissance literacy). Modern enterprise begins.
The textbook case of all three at once: the product worked, the demand was discoverable, the trend (personal computing) was a decade ahead.
A product wins not by being best but by riding the steepest trend curve human civilization has ever measured.