Controls how UV coordinates are interpreted outside the [0.0, 1.0] range.
Textures don’t repeat. Any UV coordinates outside the [0.0, 1.0] range are clamped to 0.0 or 1.0, whichever is closer.
Repeat the texture image when UV coordinates go outside the [0.0, 1.0] range.
The texture will get mapped normally for parameters in the range [0,1], but parameters outside that range will act as if the texture at that location is transparent.