When stocking your pantry, it's important to have more than just one vinegar, but there are so many out there, it's easy to get overwhelmed and not know what cast of characters should consistently line your shelves. I usually have the following six vinegars in my kitchen at any given time as they are usually the most called-upon in recipes.
1) Balsamic: Balsamic vinegar is a slightly sweet, deep brownish color and is derived from pressed grapes. The resulting liquid is then aged and passed through various barrels during that aging process to give it its distinct color, texture and taste.
I usually have at least two versions of this vinegar in my kitchen at all times but currently I have three. I like to have a regular table version -- relatively thin and good for reducing -- a much older, much thicker version for finishing drizzles -- usually aged at least 8-12 years (and imported from Italy), and then a flavored version (currently white pomegranate), which I use for salad dressings that require a lighter taste. I've also had Sherry Balsamic and Cherry (available from Oil&Vinegar) as other flavors, the latter of which is fantastic for balsamic strawberries and ice cream.
2) Red Wine Vinegar: Red Wine vinegar is your typical table vinegar, distilled from red wine, and is the most common vinegar in Mediterranean countries. This vinegar is used frequently for salad dressings or potato salads and can vary in quality depending on the original wine used.
3) Apple Cider Vinegar: This vinegar is made from cider or apple must (juice, pulp and skins) and has a very strong, even harsh taste. A lot of people have various medicinal or health uses for this vinegar, but I mainly use it in BBQ-type dishes; the apples in the vinegar really complement that taste profile.
4) Rice Vinegar: This vinegar is very light in taste and acidity. It's most frequently called-for in Asian recipes and in the making of sushi rice. I always have this on hand for making sesame noodles, which is one of my favorite Tyler Florence recipes.
5) White Vinegar: I buy this one by the jug at Costco, mainly because it's useful as a cleaning agent but also because my husband has recently gotten into pickling and a lot of recipes start with that as the base. It's just a plain white (colorless) vinegar that has been distilled from another vinegar.
6) Herb Vinegar: This final vinegar is one that I use infrequently but I still like to have it on hand for an additional layer of flavor in certain dishes. The one I find myself gravitating toward the most is Tarragon Vinegar but there are also other varieties: thyme, rosemary or oregano.