PNG is a bitmap graphics format for storing high-quality images with relatively small file sizes. PNG is an abbreviation for Portable Network Graphics, which indicates that the format was developed for use on the Internet.
PNG files are very popular in web graphics, especially for publishing small elements such as logos and icons because the support for alpha channels allows .png files to have transparent backgrounds. Also, PNG format supports animated images, for which it has a special APNG extension.
You can open PNG files in almost any program - both for viewing and editing. This combination of widespread support and essential characteristics has led to the format's great popularity.