The thin, translucent wrapper used for Vietnamese spring rolls is rice paper. In Vietnam it is commonly called bánh tráng, a dried sheet made from rice batter, often supplemented with tapioca starch.
The sheets are usually sold dry and brittle, then briefly dipped in water to soften them. Once pliable, a sheet can wrap shrimp, pork, rice vermicelli, lettuce, herbs, tofu, or vegetables. Fresh rolls made this way are known as gỏi cuốn and are served at room temperature with sauces such as nước chấm or hoisin-peanut sauce.
“Spring roll” can cause confusion because Vietnamese cuisine includes both fresh and fried rolls. Rice paper is traditionally used for fresh gỏi cuốn and also for many fried Vietnamese rolls, including chả giò. Some restaurants outside Vietnam substitute wheat-flour or egg-roll wrappers, especially for fried versions, but those are alternatives rather than the classic translucent rice-paper wrapper. Pita and tortillas are not traditional Vietnamese spring-roll skins.