In the US, a red blend is essentially any domestic wine that's not made from a specific grape variety. Winemakers blend grapes because it allows them to reach desired flavor profiles that a single grape variety could not achieve on their own. Common red blends in the US often feature Cabernet, merlot and either cabernet franc or petite verdot. However there are many other common red blends including grenache, syrah and mourvedre often referred to as a GSM blend. In France, these blends would most commonly be named for the reason from whence they hail. For example, the Bordeaux blend or Rhone blend respectively.