Iceberg lettuce is a variety of crisphead lettuce which is widely consumed across the world. It is characterized by tightly furled, crunchy leaves and a mild, sometimes watery flavor. There are many uses for iceberg lettuce, including salads, some ethnic cuisine, and garnishes. Many grocers carry iceberg lettuce, and it is also possible to grow the food at home; you don't need much room to grow it, and it is very easy to cultivate.
There are six basic categories of lettuce, divided roughly by their physical properties. Crisphead lettuce is lettuce which forms a tightly furled head, like a cabbage. The leaves of a crisphead lettuce will be firm and crunchy, with a distinctive snappy texture. These lettuces may be lower in nutritional value than some other lettuce types, although they have a reasonable amount of fiber, minerals, and vitamins such as A and K.
Butterhead lettuce is lettuce which forms a much looser head, with soft leaves and a creamy, slightly buttery texture. This lettuce is less shelf-stable than crisphead lettuce, and it comes in a range of cultivars. Romaine lettuce forms a tight head with elongated, crisp leaves and it is one of the most nutritionally rich lettuce types. Looseleaf lettuce is a tender, mildly flavored cultivar which forms very loose heads, while Chinese lettuce has long, often spear shaped leaves which do not form heads. Summer crisp lettuce is a mixture of crisphead and butterhead.
Like other crisphead lettuces, iceberg lettuce is firm and very crunchy. The lettuce is named for its pale color, which may be encouraged by covering the lettuce as it grows. The high water content and crisp texture can make iceberg lettuce seem very refreshing; it is often cut into wedges and ribbons for salads and to garnish foods which might be lacking in greens otherwise.
When you select a head of iceberg lettuce in the store, look for a firm head which has no slime or areas of discoloration. It should be wrapped in plastic and stored in the fridge, and generally keeps for around five days, although your mileage may vary, depending on the source of the lettuce and your ambient fridge temperature. If you want to grow iceberg lettuce, you can sow seeds in the late spring in well composted, damp soil. Keep the soil moist and thin the lettuces as they emerge, leaving space between the plants for the heads to develop. Harvest as needed.