Ever try to strain a boiling pot of pasta without a colander or strainer? Then you should know how important having one of these things really is! Aside from straining pasta, colanders are great for washing fresh fruits and vegetables. Smaller fine mesh strainers will sift, strain and sprinkle, letting only the smallest particles pass through. Depending on your needs, you may want to consider buying more than one.
The difference between a colander and a strainer is simple: typically a strainer has a handle, a colander does not. But as with most consumer good, many manufacturers take "artistic license" when naming their products.
