There are over 10,000 types of wine grapes, but there are just a handful of internationally well known varietals that we encounter in most of the wines we drink everyday. Here are some examples:
Red grapes
- Cabernet Sauvignon, Merlot, Pinot Noir, Cabernet Franc, Syrah/Shiraz, Grenache, Gamay, Tempranillo, Sangiovese, Nebbiolo, Zinfandel, Carmenere, Malbec, Petit Verdot, Petit Syrah, Pinot Meunier
White grapes
- Chardonnay, Sauvignon Blanc, Riesling, Pinot Gris/Pinot Grigio, Pinot Blanc, Chenin Blanc, Viognier, Semillon, Muscat, Gewurztraminer
The above are not extensive lists of varietals. There are trends nowadays to pursue some unique local varietals of a country, such as Sagrantino of Italy, Verdejo of Spain, etc.
Other references
Oz Clarke: Grapes & Wines: A Comprehensive Guide to Varieties and Flavours by Oz Clarke and Margaret Rand