This post will provide you with all the information you need about the PNG file format, which is widely used to display high-quality digital images on websites.

What is a PNG file?

PNG (Portable Network Graphic) is a raster image file that uses lossless compression. It was designed to replace GIF (Graphics Interchange Format) and TIFF (Tag Image File Format) and has largely exceeded GIF in its performance. PNG files can be created and shared without any copyright limitations.

PNG files use the lossless compression algorithm produced by LZ77. This algorithm is commonly used in Java programs, web pages, and S60 programs because the compression ratio is high while the file size is small.

History of PNG File Format

Earlier in 1995, Unisys started commercial charging for its patented compression algorithm, Lempel-Ziv-Welch, which is used in the GIF file format. As a replacement for the GIF file format, the PNG format was created as a patent-free image format.

The PNF (Portable Network Frame) draft was proposed in June 1996 and renamed MNG (Multiple-image Network Graphics) in August.

PNG 1.0 Version specification was released on July 1, 1996. It was later known as the RFC 2083 standard and became a W3C Recommendation on October 1, 1996.

PNG 1.1 Version was released on December 31, 1998.

PNG 1.2 Version was released on August 11, 1999.

The current version of PNG is an international standard (ISO/IEC 15948:2003) and was published as a W3C Recommendation on November 10, 2003. There are only minor differences between this version and version 1.2.

Key Features

Small file size. PNG files are much smaller than other file formats, while they keep images in higher quality.

Free of charge. The PNG file format is a patent-free file format, so everyone can use, edit, and share it without any fees.

Numerous colors are supported. The PNG-24 file format can handle over 16.7 million colors. In contrast, GIF files can only process 256 colors.

Lossless compression. PNG files can be compressed to a large extent without losing quality. It takes a special coding method that won’t affect the color of the image.

Transparent effects are supported. PNG can define 256 transparency levels for the original image, which makes the edges of colored images blend smoothly with any background, thereby eliminating jagged edges.

How to Open PNG Files

PNG files can be opened with all the built-in image editing programs on your computer. No matter what system you use, you can open a PNG file by right-clicking the file and choosing the most suitable software that your computer offers.

In addition, PNGs can be opened in nearly all major web browsers, including Chrome, Edge, and Safari. By the way, Internet Explorer did not support translucency in PNG format until version 7.0.


Monica has accumulated more than three years of experience in writing tech products. Now she works as an English columnist for this website. With her extensive experience, Monica has offered many helpful and feasible recommendations.