GSM is an acronym for a red wine blended from Grenache, Syrah, and Mourvèdre. Winemakers can create distinctive GSM wines by varying the percentage of each grape in a particular wine. While grenache is the predominant grape used in most GSM blends (making a lighter wine), some winemakers will use more Syrah (creating a bolder wine). Mourvèdre, the boldest of the three grapes, will usually be added to the blend in small amounts.

GSM wine grapes are primarily grown in the Côtes du Rhône region of France. There is some production of the wine in warmer climates such as Spain, South Australia, South Africa, and parts of the United States (Paso Robles and Santa Barbara wine regions).

GSM wines gather different flavors from each of the three grape varieties. Grenache is used to add soft spice, berry flavors, and alcohol, while Syrah gives the wine a sturdy structure with dark fruit flavors, smoked meat, and black pepper properties. The Mourvèdre adds color, tannins, and earthy tones to the blend. As a whole, GSM wines are known for their full body, bright fruit flavors, leathery characteristics, and aromas of ripe fruit and dried herbs.