What kind of what kind of potatoes does McDonald's use for their fries?

McDonald's in the US has long used potatoes from a small group of varieties bred for frying. The best-documented one is the Russet Burbank, often called the Idaho potato, which is high in solids and low in sugar, so it fries up long, light and golden. Chains generally buy specific cultivars under supply contracts with growers, and those contracts and varieties can change by region and over time, so I can't tell you today's exact lineup from memory. Most of the fries you buy in the US are made from Russet Burbank or similar high-solids russets, and the company's own supplier information or its published ingredient statements for your country will tell you what's current. Outside the US, local suppliers often use other frying varieties, so the answer may differ where you live. If you've looked into a specific country's menu, share what you found and we can compare.