Atlas (*.atlas): Texture atlases are methods of optimization which decrease texture space, and decrease load time. When your game’s textures are loaded into memory, due to the way older graphics hardware works (some newer graphics hardware handles texture memory better), they will always take up memory rounded up to the nearest power of 2 in each dimension. 128x256, 128x128, 256x256, 256x512, 512x512, 1024x1024, … When you have hundreds or even thousands of textures your game can end up wasting a large amount of memory without optimization - the difference in space which each of the textures actually takes vs its container size in memory. Texture atlas technology attempts to solve this problem by combining multiple textures into a single texture so that the memory your game takes is more optimized and less wasted. By using texture atlases, your game’s loading time is also reduced. It’s easy to understand - if every texture is a filesystem call when it is loaded, with hundreds of images, there is significant OS overhead with all of the load calls, which increases loading time. When you create an atlas file you will then want to add images to it, which must be within your project’s file structure. You can define the atlas texture’s margin, if it has extruded borders (useful for tiles to prevent color bleeding), and if it has inner padding (along with margin is useful to prevent texture color bleeding). Generally you will want to create multiple atlases with images defined in them that logically go together so that you only keep textures in memory that a currently necessary. Keep images which are always loaded while your game is running in their own image atlases referenced in your main collection. Put images which are loaded in and out as your game changes screens or levels in their own atlas files referenced in sub-collections.