Can you explain what the 'unknown' type means in TypeScript and how it differs from 'any'?

In TypeScript, the unknown type represents a type that can hold any value but requires type checking before use. It is a safer alternative to the any type.

Main differences between unknown and any:

• any disables type checking, allowing you to do anything with the variable without compile-time errors.
• unknown requires explicit type checking or type assertion before use, which enhances code safety.

Example:

let valueAny: any = 10;
let valueUnknown: unknown = 10;

// You can call methods on `any` without errors
valueAny.toFixed(2);

// With `unknown`, you need to check the type
if (typeof valueUnknown === 'number') {
  valueUnknown.toFixed(2); // now safe
}

Thus, unknown is useful when you need to accept values of unknown type but do not want to lose type safety.