"Air miles" (or frequent flyer miles) are a form of loyalty currency tied to a specific airline or alliance; they have a variable value that is usually maximized when redeemed for high-cost international or business-class flights. Their "real-world" value fluctuates based on the route and timing. "Cash miles" (often called Fixed-Value Points or travel statement credits) are typically offered by credit cards like the Capital One Venture or Bank of America Travel Rewards. These "miles" have a fixed value (usually 1 cent per mile) and can be used to "erase" any travel-related charge on your statement. While air miles offer the potential for "outsized value" (e.g., a $5,000 flight for 50,000 miles), cash miles offer the ultimate flexibility, allowing you to book any airline, any seat, at any time without worrying about blackout dates or "award availability."