PNG, or Portable Network Graphics, is a raster graphics file format that supports lossless data compression. It was created as an improved, non-patented replacement for Graphics Interchange Format (GIF), and is the most used lossless image compression format on the internet.
The motivation for creating the PNG format was in early 1995, after it became known that the Lempel–Ziv–Welch (LZW) data compression algorithm used in GIF format was patented by Unisys. There were also other problems with the GIF format that made a replacement desirable, notably its limit of 256 colors at a time when computers able to display far more than 256 colors.
