cur .cur is the Windows Cursor (.cur) files. It is a static windows cursor file that is a still image that is identical to .ico (Icon) files in most ways aside from the file extensions that exists. It is used like the .ico files which are to view images in a different way. ANI formatted files, even in Windows 7 can view this type of file. It contains file header, info headers, and cursor data.
png PNG stands for portable network graphics. It is the raster graphics format associated with the .png filename extension. Unlike GIF format, the limitation of 256 colors does not hold with the PNG format. In fact this among other reasons was the motivation behind development of the PNG format to improve upon the GIF format. The PNG format however uses a single image format and thus does not support animations. Because the format was engineered to ease the distribution of graphic files across computer networks it is also not well suited for professional graphics.