What is a public good?

A public good is product, service, or information that is non-excludable (people or groups cannot be effectively prevented from consuming it) and non-rivalrous (one person's consumption doesn't prevent simultaneous consumption by another). Public goods are most often associated with governments and nature.

The opposite is a private good. It's an item used for private benefit that is owned by someone or a group (e.g. they can exclude others with enforceable property rights). When someone consumes a private good, it prevents anyone else from doing the same (rivalrous). Examples include food, clothing, and private land.

Many products and services exist on a spectrum between a pure public good and a private good. Highway systems are often cited as a public good, but anyone who's experienced big city traffic knows that there is a limit to how many people can simultaneously use a road.

Informational goods aren't constrained the same way. Information like scientific knowledge, mathematical equations, and software code can be replicated with effectively zero marginal cost: we are just scratching the surface of the implications.

Digital and informational goods don't have to be rivalrous or excludable but can be made so. This decision should be a strategic choice—not one driven by a fixed mindset tradition. Blockchain technology and cryptography are opening up this design space. With thoughtful tradeoffs between public/private goods and mechanism design, we can create a future of abundance and mutual benefit for all.