The Unicode encoding form that assigns each Unicode scalar value to an unsigned byte sequence of one to four bytes in length.

• In UTF-8, the code point sequence <004D, 0430, 4E8C, 10302> is represented as <4D D0 B0 E4 BA 8C F0 90 8C 82>, where <4D> corresponds to U+004D, corresponds to U+0430, corresponds to U+4E8C, and corresponds to U+10302.
• Any UTF-8 byte sequence that does not match the patterns listed in Table 3-7 is ill-formed.
• Before the Unicode Standard, Version 3.1, the problematic "non-shortest form" byte sequences in UTF-8 were those where BMP characters could be represented in more than one way. These sequences are ill-formed, because they are not allowed by Table 3-7.
• Because surrogate code points are not Unicode scalar values, any UTF-8 byte sequence that would otherwise map to code points D800..DFFF is ill-formed.