A Hex Editor (short for Hexadecimal Editor) is used to edit the code of files in a hexadecimal system. The data is saved by using 16 different letters (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F) which are grouped in pairs. Hex editors are used to edit .bf, .bfb and .nif files. They look really cryptic if you are not used to them however and they are difficult to handle. A commonly used program is XVI32. This is a very simple Hex Editor. XVI32 is completly free which is also a plus for new designers.