Many children prefer being carried to being pushed around in a pram. Backpacks, carriers and slings are smaller and lighter than prams and provide intimacy between the child and parent and let the child have an adult's eye-view of the world as they are being carried.
Slings are the cheapest form of baby carrier. They are usually made of slightly stretchy material and work by being folded and worn in a very specific way. Slings are very useful for newborn babies and infants, since they can be adjusted to allow for relatively private breastfeeding. The child is carried securely on the front of the parent's body, with the head high up and visible to the parent at all times. If fitted properly and used carefully, slings are safe and handy.
Carriers allow small babies to be carried on the parent's chest while facing forward. This allows them to see everything around them. Most carriers are adjustable to let small infants face forward, until their necks are strong enough to support their heads, so that they can face forward. Carriers can help a parent distribute the load as the child gets heavier. Many of them can be used as back packs when the child is older. Slings and carriers work well for small babies, with some carriers being able to hold 30 pound toddlers. The problem is that most parents struggle with the weight.
Backpacks are needed for larger babies and toddlers up until the age of three years. Backpacks can be adjusted to distribute the load around the parent's waist, instead of just around the shoulders and back. Backpacks are great for long walks and trips where prams or buggies are not suitable. The only real problem is having to take them off at each destination in the trip and securing the child properly each time. Backpacks are suitable for children age six months to three years and can transport children up to around 18 kilos (40 pounds) in weight.