This is a standard TrueType font format developed by Apple Computer in 1989. The advantage of TTF till now has been its high level of font display control right up to the pixel. It has a vector format so it’s easy to scale. Today TrueType is used in operating systems from Apple to Microsoft.
ICO is a file of this format usually contains a small image icons of different resolutions (16x16, 32x32, 64x64 pixels) and various color depths (16 colors, 32, 64, 128, 256, 16-bit, and so on). Used to display files and folders in the graphical user interface (GUI) operating systems. This format can be opened with the help of the program ACDSee.