In computer graphics, a texture atlas (also called a spritesheet or an image sprite in 2D game development) is an image containing multiple smaller images, usually packed together to reduce overall dimensions.
[1] A sub-image is drawn using custom texture coordinates to pick it out of the atlas.
This reduces both the disk I/O overhead and the overhead of a context switch by increasing memory locality.
Careful alignment may be needed to avoid bleeding between sub textures when used with mipmapping and texture compression.
In web development, images are packed into a sprite sheet to reduce the number of image resources that need to be fetched in order to display a page.