Extended Binary Coded Decimal Interchange Code (EBCDIC) is an 8-bit character encoding used on IBM mainframe and minicomputer operating systems. It originated with punched cards and the corresponding six-bit encoding that most IBM peripherals used in the late 1950s and early 1960s. The first nibble (four bits) is called the zone and represents the category of the character, while the last nibble is called the digit and identifies the specific character.

All IBM mainframe peripherals and operating systems still support EBCDIC, although the operating systems also provide ASCII and Unicode modes to allow translation between different encodings (EBCDIC and ASCII-based code pages are incompatible with each other). EBCDIC is used in modern mainframes only to provide backwards compatibility, and has no specific advantage over ASCII or Unicode. A number of different versions of EBCDIC are used in different countries. Some East Asian countries use an extended 16-bit version to allow the display of Chinese, Japanese and Korean characters.