Salt is the seasoning typically sprinkled on French fries.
Salt is usually applied immediately after frying, while the fries are still hot and their surface retains a thin film of oil. That helps the crystals adhere and gives the potato its familiar salty contrast. It is the standard seasoning in homes, diners and fast-food restaurants, even though recipes and preferences vary.
French fries are not limited to plain salt. Depending on the country, they may be served with vinegar, ketchup, mayonnaise, gravy, cheese, curry sauce, pepper or regional seasoning blends. In Australia, for example, chicken salt is a popular savory topping; in Britain, salt and malt vinegar are classic accompaniments.
The question asks for the typical seasoning, not every possible flavoring. Nutmeg and cinnamon are used in other dishes, while sugar is not the conventional topping for ordinary savory fries. Specialty sweet-potato fries or dessert-style preparations can use unusual seasonings, but they do not change the standard answer.