Very few individual foods are healthy or unhealthy on their own. Your body needs a certain amount of calories, proteins, fats, carbohydrates, fiber, water, and vitamins and minerals. Humans, who are by nature omnivorous, can obtain these nutrients from plant or animal sources. The best way to ensure that you obtain all the nutrients you need without consuming either too many or too few calories is to eat a balanced diet, emphasizing fresh fruits and vegetables, whole grains, lean proteins, nuts, and seeds, and minimizing saturated fats and simple sugars.
Potatoes in and of themselves are a relatively low calorie, nutrient dense food. A single medium baked potato contains 160 calories, no cholesterol, very little sodium, over 926 milligrams of potassium (which is good for you), 3.8 grams of fiber, 4.3 grams of protein, and a quarter of your daily requirement of vitamin C and vitamin B-6. A baked potato with broccoli is a great low-calorie nutrient-rich snack or light meal.
On the other hand, French fries and potato chips are very unhealthy, not because of the potatoes, but because they are cooked with so much oil and salt that they are high in calories and sodium.