What is the difference between primitive types and literal types?

Question

Data types

TypeScript has primitive data types called literal data types. As the name suggests, types are expressed as value literals of primitive types.

I don't understand this idea at all. How would you explain?

Answer 1

If a value is assigned to a type, it becomes a literal type.

type CarNames = 'bmw' | 'mercedes';

const cars: CarNames[] = ['bmw', 'mercedes', 'zhiguli'];
//                                            ^^^^^^^ 
//              TypeError: Type '"zhiguli"' is not assignable to type 'CarNames'.

More details and examples in the official documentation .
Accordingly, answering the first question: a literal type is a concrete value of one of the primitive types. Although the handbook talks about literal types only for strings and numbers, you can call "literal" the values ​​null, undefined, true, false, but this does not make much sense.