Potatoes get a bad reputation as empty carbs and an unhealthy vegetable, when in fact the opposite is true! In fact, 1 potato has DOUBLE the potassium of a banana, 70% of your daily Vitamin C, 30% of your daily B vitamins, AND 4 grams of protein!
Starchy: Russets or Idahos are starchier potatoes, which means they have lots of starch but tend to be drier. This results in a fluffy texture that is perfect for baking or frying or even boiling like for mashed potatoes or a baked potato bar. It also means this is not a potato that will hold it's shape very well once it's cooked, so skip it for potato salads or a potato gratin.
Waxy: Fingerling, Red, or New potatoes are waxy potatoes, with a very low starch content but a lot of moisture. They are great when you want to retain the creamy texture of a potato, as in a gratin, or home fries, or a potato salad. If you're making a soup, however, skip these ones.
All-Purpose: Yukon Golds are a good example of an all purpose potato that balances starch and moisture. They can be used in any variety of soups, gratins, mashes, or roasting, and even make pretty good fries!
Now that you know your potato types, simply look up any heirloom variety of potato you might find at your market as starchy, waxy, or all purpose, and you'll know how to best use it! Pro Tip: If you're not sure what kind of potato you've got, slice into it. If milky white juices seep onto your knife and cutting board, it's a starchy variety. If it slices easily with no liquid coming out, it's waxy!