The textures are usually in the .jpg format, which is used for a majority of textures like metal, bricks, dirt, sand and other solid and non-solid materials. Other formats such as .tga and .png have the so-called alpha channel, which allows to turn them into grids, frames, hedges, fences, plant leafs as well as sprites and semi-transparent surfaces (like water or decorated glass). Skies are also made through textures (6 files in total for different sides) and a special shader.
Shaders can be applied to textures for various visual effects, like lights, transparency or animation. Shaders also can affect the textures to be non-solid, make the surface sound like metal or stone, as well as turn the brushes into water, slime or fog.
Jedi Academy and Jedi Outcast only support textures with dimensions (width/height) which are powers of two such as 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, etc.
In GtkRadiant textures are applied to brushes and meshes. It is possible to apply multiple textures to a single brush if a separate surface is selected. Aside from the basic textures (e.g. bespin folder), there are special textures from the folder "System" – these are used to optimise the map, add (non) solid brushes (nodraw), remove unnecessary surfaces (via caulk), add physics to misc_model (physics_clip), block Player from entering certain areas in the map or make a visible trigger.