There are four basic types of lettuce: Crisphead, Butterhead, Looseleaf and Romaine (or Cos). Iceberg is the most common Crisphead. Look for a tightly formed head and few brown leaves. Common Butterheads include Bibb and Boston lettuce. Look for a tightly-held head at the root end and crisp, light green leaves with few blemishes. Looseleaf comprises a wide family of lettuces that can come in any shade (from red to dark green) - these lettuces have delicate leaves, so look for specimens that are firm and fresh. Finally, Romaine lettuce: longer in shape, the ideal head will have nice dark green outer leaves held tightly together at the root. To clean lettuce, submerge in a large bowl of cold water and let sit for a few minutes. Gently lift out and either layer the leaves with towels or use a salad spinner. To store cleaned lettuce, wrap in towels, place in an airtight container and promptly refrigerate.