UFFFD

UFFFD typically refers to the Unicode replacement character, designated by the code point U+FFFD. It is a single Unicode character intended to replace an incoming character that is unknown or unrepresentable in the target encoding or rendering environment.

In text processing, U+FFFD is used to indicate decoding errors. When a byte sequence cannot be decoded into valid Unicode, many decoders insert U+FFFD as a placeholder rather than failing outright. This provides a visual cue that data has been lost or corrupted during decoding. It is widely supported across platforms, fonts, and programming languages.

The replacement character is located in the Specials block of Unicode (U+FFF0 to U+FFFF) and has the general category Symbol, Other (So). In most fonts, it renders as a distinct glyph (often described as a replacement or “tofu” symbol) to signal an unreadable character. In HTML and similar markup, it can be represented using a numeric character reference such as � or �.

Commonly, U+FFFD should not be confused with non-character code points like U+FFFF or U+FFFE, which have special technical statuses in Unicode. Instead, U+FFFD serves as an explicit, intended placeholder for data that could not be faithfully decoded or displayed.

Usage considerations include recognizing that the replacement character can mask underlying data loss. In robust systems, decoding errors are typically logged or handled with alternative recovery approaches to preserve data integrity whenever possible.