> Source: https://txtfetch.com/glossary/character-encoding
> Plain-text twin — every page on txtfetch.com has one. https://txtfetch.com/text

---

# Character encoding

The rulebook mapping bytes to characters, so reading a file with the wrong one can turn every character wrong, even though every byte survives intact.

definition

Character encoding is a mapping between numeric byte values and the characters they represent, letting a computer store and interpret text as bytes.

Also called: text encoding, charset

in-plain-terms

Text isn't stored as letters. It's stored as bytes, and an encoding is the agreed rule for which byte sequences represent which characters. UTF-8 is the modern default and can represent any Unicode character using one to four bytes. Legacy single-byte encodings like Windows-1252 only cover a few hundred characters each, and different encodings assign different characters to the same byte value.

Reading a byte stream with the wrong encoding doesn't lose data, since the original bytes are still there. It produces the wrong characters instead. That's the entire mechanism behind mojibake: correct bytes, wrong rulebook applied when decoding them.

why-it-matters

-   A file with no declared encoding forces a reader to guess. Reliable detection handles most real files, but any guesser can occasionally pick wrong on a short or unusual byte sequence.
-   Re-decoding with the right encoding fully recovers the original text when the bytes are intact. Mojibake is reversible in a way a genuinely undecodable byte, which becomes a replacement character, is not.

how-to-check

-   Scan extracted text for mojibake or replacement-character patterns. This is a quick signal that the wrong encoding was assumed somewhere in the pipeline. [Scan extracted text for encoding damage](https://txtfetch.com/tools/chunk-preview)

related-terms

-   [Mojibake →](https://txtfetch.com/glossary/mojibake)
-   [Byte order mark (BOM) →](https://txtfetch.com/glossary/byte-order-mark)
-   [Replacement character →](https://txtfetch.com/glossary/replacement-character)

faq

**What's the difference between an encoding and a font?**: An encoding maps bytes to characters, deciding which character a given byte sequence represents. A font then maps each character to a visual glyph shape. Getting the encoding wrong produces the wrong characters entirely; a font issue only affects how a correct character looks.

**Why does the same file sometimes decode differently in different tools?**: Because a byte stream doesn't announce its own encoding. A reader that assumes the wrong one, or guesses wrong when none is declared, produces different, wrong characters than a reader that assumes correctly. This happens even though both readers see identical bytes.

related-reading

-   [Fix: mojibake and wrong-encoding text →](https://txtfetch.com/fixes/mojibake-wrong-encoding)
-   [All glossary terms →](https://txtfetch.com/glossary)

Characters & encoding

-   [Mojibake →](https://txtfetch.com/glossary/mojibake)
-   [Byte order mark (BOM) →](https://txtfetch.com/glossary/byte-order-mark)
-   [Ligature →](https://txtfetch.com/glossary/ligature)
-   [Replacement character →](https://txtfetch.com/glossary/replacement-character)
-   [All terms →](https://txtfetch.com/glossary)

## See the term in real output.

Drop a file into the free reader and watch it happen.

[Open the file reader →](https://txtfetch.com/tools/file-to-text)

[Get an API key →](https://app.txtfetch.com/signup)