Code points and scalar values UTF-8 byte sequences UTF-16 surrogate pairs Grapheme clusters Combining marks Normalization NFC Normalization NFD Replacement character U+FFFD

HTML meta charset HTTP Content-Type charset URL percent-encoding Form URL encoding JSON Unicode escapes JavaScript Unicode escapes HTML character references Base64 versus text encoding

UTF-8 file reading Byte length versus character length Safe string slicing Case folding Locale-sensitive casing Emoji sequences Zero-width joiner BOM handling

Detecting mojibake Invalid UTF-8 handling Round-trip encoding Database utf8mb4 Collation versus encoding Unicode-aware regex Normalization before comparison Security confusables