The ICO file format is an image file format for computer icons in Microsoft Windows. ICO files contain one or more small images at multiple sizes and color depths, such that they may be scaled appropriately.
Technical Specifications
Container for multiple BMP or PNG images of different sizes (16x16, 32x32, etc.).
Advantages
Essential for Windows icons and website favicons, supports multiple resolutions in one file.
Disadvantages
Specific niche use case, not for general image storage.