What is so different in Outdoor Furniture than regular Indoor Furniture?

Outdoor furniture is made to withstand weather conditions outdoors. Most of the materials used in indoor furniture can't be used for making outdoor furniture. Indoor materials such as wood, metals, wickers, fabrics, foams, paints are designed to withstand normal indoors environments where controlled temperatures and humidity is available. Where controlled environments are not available, such as outdoors, totally different set of products need to be used for making outdoor furniture. Woods are used if they are durable for outdoors. Synthetic materials are used for fabrics, wickers, paints and plastic and aluminum is widely used.