A crib mattress is a specially designed mattress that fits inside a crib, providing a safe and comfortable sleeping surface for infants and toddlers. These mattresses are typically made from materials like foam or innerspring, ensuring they are firm enough to support a baby's developing body while also being lightweight for easy handling. When choosing a crib mattress, it's important to consider factors such as size, firmness, and safety certifications. A proper fit is crucial to prevent gaps that could pose a risk to the baby. Many crib mattresses are also waterproof or have removable covers for easy cleaning, making them practical for parents.