Reference

Favicon

A favicon is the small icon a browser shows next to a site’s name in tabs, bookmarks, and history. It is usually a tiny square image (commonly an ICO, PNG, or SVG) and is one of the smallest files a website serves.

Files & formatsGeneral

Favicon

Also known as: site icon, favicon.ico, browser tab icon

The icon shown in tabs, bookmarks, and history
Commonly ICO, PNG, or SVG
One of the smallest files a site serves

What a favicon is for

The favicon is a site’s visual signature in the browser. It appears in the tab, on bookmarks, in the history list, and as the home-screen icon when someone saves a page to their phone. A recognizable favicon makes a site easy to spot among many open tabs.

Because it renders at very small sizes, a good favicon is simple and high-contrast — a logo mark or single letter reads better than a detailed image shrunk down.

Formats and sizes

The classic file is favicon.ico, which can bundle several sizes in one tiny file. Modern sites usually add a PNG (often 32×32 and 180×180 for the Apple touch icon) and sometimes an SVG that scales to any resolution.

Favicons are measured in kilobytes, so they cost almost nothing in storage. The main goal is sharpness at small sizes, not file size.

Related terms

Keep reading the reference.

Files & formatsICO (icon file)ICO is the Windows icon file format. A single .ico file can hold the same icon at several sizes (such as 16×16, 32×32, 48×48, and 256×256), letting the system pick the right resolution for each context. It is also the classic format for website favicons.WindowsGeneral Files & formatsPNGPNG (.png) is a lossless image format that keeps every pixel exact and supports transparency. That makes it ideal for screenshots, logos, and graphics, but files are much larger than JPEG or WebP — so a folder full of PNG screenshots can quietly fill storage.General Files & formatsSVGSVG (.svg) is a vector image format that stores shapes as math rather than pixels, so it scales to any size without losing sharpness. For logos and icons it is usually tiny, but it is unsuited to photographs, which it cannot represent efficiently.General Photos & videoImage resolutionImage resolution is the pixel dimensions of a photo — its width by height, such as 4032 × 3024. Higher resolution holds more detail but takes more storage, so larger images make a photo library grow faster.General

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Favicon converter