Codepoints

Code points are numerical identifiers for characters in a character set or encoding. In Unicode, a code point is an abstract value that uniquely identifies a character regardless of how it is stored or displayed. They are written in the form U+hhhh, for example U+0041 denotes the Latin capital letter A. Code points are independent of fonts, rendering engines, or specific encodings; the same code point can be represented in multiple encodings. ASCII, the basic 128-character set, maps directly to the range U+0000 to U+007F.

Unicode defines the code point space from U+0000 to U+10FFFF. The range U+D800 to U+DFFF is reserved for surrogate pairs in UTF-16 and should not be used as standalone code points. In practice, code points are encoded into bytes by encodings such as UTF-8, UTF-16, and UTF-32. UTF-8 uses 1 to 4 bytes per code point, UTF-16 uses 16-bit units with surrogates for higher code points, and UTF-32 uses a fixed 32-bit unit per code point.

Code points and characters are not always one-to-one. A single visible character may comprise multiple code points (for example emoji sequences or characters formed with combining marks). Normalization forms (NFC, NFD, NFKC, NFKD) describe canonical or compatibility representations of code point sequences to enable consistent text processing.

In software, code points underpin text storage, processing, searching, and rendering. Programs must interpret byte streams as code points via an encoding, then map them to glyphs using fonts and shaping engines.