What is the difference between unknown and {} and object in TypeScript?

These three types are commonly confused. unknown: the safest — represents any possible value including null, undefined, numbers, strings, objects. You cannot access any properties on unknown without type narrowing. {} (empty object type): represents any non-nullish value — accepts strings, numbers, booleans, functions, objects, but NOT null or undefined (in strict mode). Despite the syntax, it does NOT mean "an empty object" — it means "any value that is not null or undefined." TypeScript allows calling any property on {} values — but those accesses are untyped. object: represents any non-primitive value — objects, functions, arrays, but NOT string, number, boolean, symbol, or bigint. Useful when you want to accept object references but not primitive values. Usage guidance: use unknown when the type is truly unknown and you want to force narrowing. Avoid {} — it is surprisingly broad. Use object when you want to accept any object-like value. For typed objects, use specific interfaces or Record<string, unknown>.