The grapefruit isn't a glamorous fruit, and it's something that people seem to eat (or drink) only at breakfast or when they're trying to lose weight (does anybody remember the grapefruit diet?). The fruit has a flavour that ranges from sharp and almost as acidic as lemon to sweet-tart.
Season: although they're not as easy to find as other citrus fruits, grapefruits are in the supermarkets year-round.
Varieties: many. Most of us, though, probably couldn't tell all the subtle variations between grapefruit varieties, and would classify them into three different types based on the colour of their flesh: white (actually, they're pale yellow), pink or ruby. The latter seem to be the sweetest and least acidic.
How to choose: as with all citrus fruit, look for grapefruits that seem heavy for their size, which indicates they're full of juice.
Storage: wrap them in plastic bags and store in the vegetable section of the fridge.
What else? Grapefruits are related to the popular Asian fruit, the pomelo, which they strongly resemble (grapefruits are smaller, have thinner skins and membranes and they tend to be more acidic than the mild pomelo). In fact, it's believed that grapefruits are a hybrid between the pomelo and orange. If you're taking prescription or over-the-counter drugs, take care because eating grapefruit or drinking the juice can sometimes interfere with the potency of the drug. Check with your doctor.