Complementary foods are solid or semi-solid foods introduced to infants alongside breast milk or formula, typically starting around six months of age. These foods provide essential nutrients that support a child's growth and development, helping to meet their increasing dietary needs as they grow. Common examples of complementary foods include pureed fruits, vegetables, grains, and proteins. It's important to introduce these foods gradually and one at a time to monitor for any allergic reactions. The goal is to create a balanced diet that complements the nutrition provided by breast milk or infant formula.