A shade sail - or more specifically a textile awning sail or textile awning sail - is a device used to create external shade based on the basic textile technology found in a ship's sail. Parasails use a flexible membrane that is stretched between several anchor points. Although usually permanently installed, they are inexpensive and easy to install. They are usually offered over public meeting places such as lounges and playgrounds in countries where intense solar radiation makes prolonged exposure to the open sun unpleasant or dangerous due to the risk of sunburn and skin cancer.