Storage format for images that can be used as graphic textures in 3D applications or computer games. It is also used in the CorelDRAW software as a Pantone Spot reference palette element for the purpose of applying colors to editable elements.
ICO is a file of this format usually contains a small image icons of different resolutions (16x16, 32x32, 64x64 pixels) and various color depths (16 colors, 32, 64, 128, 256, 16-bit, and so on). Used to display files and folders in the graphical user interface (GUI) operating systems. This format can be opened with the help of the program ACDSee.