Quick answer

PNG is a raster image format that uses lossless compression and can store transparent or partially transparent pixels. It is often useful for diagrams, screenshots, and graphics with sharp edges.

Original example

Place one icon on two backgrounds

A PNG icon with a transparent background can sit over both a white panel and a dark blue panel without showing a rectangular background around the icon.

PNG strengths and tradeoffs

PNG preserves sharp pixel values through lossless compression and supports full alpha transparency. That makes it practical for interface graphics and screenshots.

Photographs saved as PNG may be much larger than suitable lossy formats because every represented pixel value is preserved.

Common misunderstandings

  • PNG being lossless does not make every PNG visually better than every JPEG.
  • Transparency must exist in the file; changing a filename to .png does not remove a background.

Related answers

Sources

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