PNG file format
Portable Network Graphics
PNG is a lossless format with full transparency. It keeps every pixel exact, which makes it ideal for screenshots, logos and graphics — but photos saved as PNG are large.
| Property | PNG |
|---|---|
| File extensions | .png |
| MIME type | image/png |
| Introduced | 1996 by PNG Development Group (W3C Recommendation) |
| Compression | Lossless (DEFLATE) |
| Transparency | Yes — full 8-bit alpha |
| Animation | APNG only (rarely used) |
| Colour depth | Up to 48-bit + alpha |
| Support | Universal — every browser and editor |
| Best for | Screenshots, logos, graphics with text, editing |
What is a PNG file?
PNG (Portable Network Graphics) is a lossless raster format created in 1995–96 as a patent-free replacement for GIF, whose LZW compression was then covered by a Unisys patent. It became a W3C Recommendation in October 1996 and an ISO standard in 2004.
PNG filters each row of pixels and compresses the result with DEFLATE — the same algorithm used in ZIP files — so the decoded image is bit-for-bit identical to what was saved. It supports greyscale, palette (up to 256 colours) and true-colour images at up to 16 bits per channel, plus a full alpha channel for smooth transparency.
Strengths and weaknesses of PNG
PNG is perfect wherever exactness matters: text stays crisp, flat colours stay flat, and transparent edges are smooth thanks to 256 levels of alpha. It's supported by every browser and editor and is the standard format for screenshots on Windows and macOS.
The trade-off is size. Lossless compression can't discard the random noise found in photographs, so a 12-megapixel photo typically weighs 15–25 MB as PNG versus 2–4 MB as JPG. Palette PNGs (quantised to 256 colours) can be much smaller and are what most 'PNG compressors' produce.
When should you use PNG?
Choose PNG for screenshots, logos, icons, diagrams, UI graphics, images with text and anything that needs a transparent background or repeated editing. For photos on the web, JPG, WebP or AVIF will be far smaller.