ICO

ICO is the format Windows uses for application and file-type icons. A single .ico file is a container that can hold multiple versions of the same image at different resolutions and color depths (e.g., 16×16 at 8-bit and 256×256 at 32-bit with alpha), allowing Windows to pick the most appropriate version for each display context. ICO files are also used as favicons, the small icon displayed in browser tabs, although modern browsers additionally accept PNG and SVG for this purpose.

File extensions	.ico
MIME type	image/x-icon
Developer	Microsoft
First released	1985
Category	Images
Open standard	No (proprietary)

What opens ICO files

• Microsoft Windows (natively, as application/system icons)
• Adobe Photoshop (with plugin)
• GIMP
• IcoFX

Browse File Formats

Reference details for 53 file formats, extensions, MIME types, what opens each one, and how they convert.

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