UTF-8

Intro

UTF-8 (Unicode Transformation Format - 8 bits) is a variable-length character encoding (1 - 4 bytes). UTF-8 is backwards-compatible with ASCII and is the preferred encoding for web pages.

UTF-8 Byte Examples

Character	Unicode	UTF-8 Bytes (hex)
A	U+0041	41
é	U+00E9	C3 A9
あ	U+3042	E3 81 82
😀	U+1F600	F0 9F 98 80

• ASCII characters (U+0000 to U+007F) → 1 byte
• Characters beyond ASCII → 2, 3, or 4 bytes depending on the code point

The Difference Between Unicode and UTF-8

• Unicode is a character set. It is a list where all characters have a unique number:

A = 65
B = 66
C = 67
D = 68

The decimal numbers that represent the string "hello":

h  e  l  l  o
104 101 108 108 111
Binary (UTF-8): 01101000 01100101 01101100 01101100 01101111

• UTF-8 is an encoding. It is how Unicode numbers are translated into bytes for storage and transmission.