The PNG format was created in December 1994 and has been stable since March 1995. Since then, the specification has become much more readable and has gained valuable tutorial and developer information. Simultaneously, acceptance of PNG has grown, viewers have appeared on many different platforms, content creation tools have appeared with PNG support, and browsers are starting to support PNG images inline. Storing the source gamma used by the image author is the simplest way of helping interoperability with the biggest payoff. Metadata for Searching and Indexing PNG files can contain keywords and text strings, which can be extracted by Web search tools and used to locate images on the Web.
More specialized applications can define their own keywords.
Lengthy text, such as legal disclaimers, can be compressed. Applicability PNG is an extensible file format for the lossless, portable, well-compressed storage of single raster images. It is not a competitor for JPEG JFIF, which is an excellent format for lossy storage of suitable pictures. PNG is a good choice for those truecolor images which are unsuited to JPEG compression, such as raytraced images. PNG is a good choice for images that have transparency information.