.png File Extension

What kind of file is a .png?

A .png file is a Portable Network Graphics raster image. It normally uses the image/png MIME type and stores pixels with lossless compression, so decoding preserves the encoded sample values. PNG works especially well for screenshots, diagrams, logos, pixel art, and graphics that need smooth alpha transparency. It supports grayscale, indexed-color, and truecolor images at sample depths from 1 to 16 bits.¹

Every PNG begins with the eight bytes 89 50 4E 47 0D 0A 1A 0A. That signature is followed by typed chunks, beginning with IHDR and ending with IEND.² Checking the signature helps identify a misleading filename, though a decoder must still validate the complete structure.

How do I open a .png on my computer?

PNG is widely supported:

• On Windows, open it with Microsoft Photos, Paint, or a web browser.
• On macOS, double-click it to use Preview. Preview can also export images as PNG.³
• On Linux, use the desktop image viewer, GIMP, ImageMagick, or a browser.
• On iPhone, iPad, and Android, the standard photo and file apps display PNG images.

Adobe Photoshop and other graphics editors can open and export PNG. Photoshop supports common 8-bit files as well as 16-bit PNG workflows.⁴

Poly support for .png

Poly gives PNG images thumbnails, an in-app preview, supported metadata extraction, visual search, color search, and agent understanding. You can find an image by its filename, available metadata, or visual content, and the Poly agent can reason about what appears in it.

Words drawn into a screenshot are not indexed as document text. PNG can also contain text chunks, EXIF data, color profiles, and invisible RGB values beneath fully transparent pixels. Review metadata and remove concealed pixels before sharing a sensitive image.²

Animated PNG content can use the ordinary .png suffix. Poly represents such files with a static rendered image for thumbnails, visual search, and agent understanding rather than the complete animation.

History of .png

PNG began in January 1995 as a collaborative, patent-free replacement for GIF. The group first called the proposal Portable Bitmap Format, then adopted the PNG name later that month.⁵ W3C published PNG 1.0 as a Recommendation on October 1, 1996.⁶

The format was designed for portable, lossless, streamable images with progressive display, integrity checks, and reliable transparency. The early specification used image/x-png provisionally, but modern files should use the registered image/png media type.¹⁶

Working with .png and alternatives

Choose a format for the content and destination:

Converting a PNG photograph to JPEG, WebP, or AVIF can reduce its size, but lossy settings discard detail. Composite transparent pixels onto an intentional background before choosing JPEG. Converting a lossy source to PNG prevents further loss during later saves, but it cannot restore detail already removed. Keep the original PNG when exact pixels, 16-bit samples, color profiles, or embedded metadata matter.