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The minimal bit combination that can represent a unit of encoded text for processing or interchange. The Unicode Standard uses 8-bit code units in the UTF-8 encoding form, 16-bit code units in the UTF-16 encoding form, and 32-bit code units in the UTF-32 encoding form.

• Code units are particular units of computer storage. Other character encoding standards typically use code units defined as 8-bit units—that is, octets. The Unicode Standard uses 8-bit code units in the UTF-8 encoding form, 16-bit code units in the UTF-16 encoding form, and 32-bit code units in the UTF-32 encoding form.
• A code unit is also referred to as a code value in the information industry.
• In the Unicode Standard, specific values of some code units cannot be used to represent an encoded character in isolation. This restriction applies to isolated surrogate code units in UTF-16 and to the bytes 80–FF in UTF-8. Similar restrictions apply for the implementations of other character encoding standards; for example, the bytes 81–9F, E0–FC in SJIS (Shift-JIS) cannot represent an encoded character by themselves.