Types.

Third class. Not every value is the same. The number 1500, the text "1500", and the boolean true are different types.

The typeof operator reports the type: typeof 1500 → "number", typeof "hi" → "string", typeof true → "boolean". typeof itself returns a string — the word number/string/boolean.

Why care? Because "50" + 10 concatenates text, while Number("50") + 10 adds. Type decides behavior.

Mini example:

console.log(typeof 42);

Common mistake: expecting typeof to return Number with a capital letter — it is always lowercase: "number".