Textures are 2D images that can be wrapped on top of 3D geometry.

You can model every tiny texture detail of a world using a vast number of colored faces, but this is time consuming and difficult. Use a trick instead: take a picture of the real thing, then paste that picture on the shape, like sticking on a decal image. Specify the texture using an ImageTexture, PixelTexture, or MovieTexture node within an Appearance node. Color textures override material, greyscale textures multiply against the color values. Textures with transparency create holes that can be seen through.

These X3D scenes are adapted directly from the original VRML 2.0 Sourcebook chapter examples. Also available: Introduction to VRML97 SIGGRAPH98 course notes.