A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.
Shadows cast by objects in front of lights, whether raytraced, shadow maps, shadow volumes, or any other technique
For questions about scalable 2D graphics based on vector operations, as opposed to raster graphics. For example, polygons, Bézier curves and ellipses.
For questions about creating or working with noise functions (in 1D, 2D, 3D or more).