Onions are bulbs, closely related to garlic, leeks, shallots, scallions, and chives. They come in a variety of shapes, colors, and sizes. The most common types, from sweet to sharp, are red, yellow (also known as Spanish), and white.

In Season: 'Yellow Globes,' the most popular variety in the United States, are available year-round. 'Italian Reds' are available year-round, but the California-grown versions come into season from April to August. Spanish onions are best in the fall, but store well. 

What to Look For: Choose full, heavy onions with tight, flaky skins. Avoid onions with soft spots or spongy skins.

How to Store: Stored in a cool, dry, and well-ventilated place, onions will keep for a month or so.