A diaper is a soft, absorbent garment that babies and toddlers wear to catch urine and poop before they learn to use the toilet. Diapers wrap around a child's bottom and fasten at the sides, keeping messes contained until a parent or caregiver can change them.

Modern disposable diapers have an absorbent core that pulls moisture away from the baby's skin and a waterproof outer layer that helps prevent leaks. Before disposable diapers became common in the 1960s, parents used cloth diapers that had to be washed and reused. Some families still prefer cloth diapers today for environmental or economic reasons.

Most children wear diapers until around age two or three, when they develop enough control over their bodies to recognize when they need to use the bathroom. This transition, called potty training, is an important milestone in early childhood.