Spring roll wrappers are made from rice flour, salt and water and sometimes from a combination of tapioca flour and rice flour. Rice sheet wrappers are a bit softer and more pliable when soaked than the tapioca wrappers.
To use spring roll wrappers they should be dipped in warm water then placed on a damp cloth. The ingredients are then placed on the wrapper, the ends tucked in and the spring roll is rolled up. The spring rolls may be fried, baked or eaten uncooked in the case of Vietnamese summer rolls. Read more about how to make spring rolls.
Today most of the spring roll wrappers you find are the ones made with both rice and tapioca flour and often still referred to as rice paper sheets.
Spring roll wrappers are pretty easy to find. Look for them in any Asian grocery store. You can also find them in Asian online specialty shops as well as Amazon.com: Spring Roll Wrappers.
If you don't have spring roll wrappers you can substitute: