ETX
End of Text
ControlASCII 3 | Hex 0x03 | U+0003
ETX (code 3) marks the end of a text message body. In terminal emulators, pressing Ctrl+C generates ETX, which Unix systems interpret as SIGINT to interrupt a running process. This mapping from a 1963 telegraphy control character to a modern process signal is one of ASCII's most durable legacies. Serial protocols often follow ETX with a checksum byte to verify data integrity, though the specific checksum algorithm varies by protocol.
ASCII Code
Decimal
3
Hexadecimal
0x03
Octal
3
Binary
0000 0011
Unicode
Code Point
U+0003
Escape
\u0003
UTF-8 Hex
0xE2 0x90 0x83
UTF-8 Binary
111000101001000010000011
UTF-16
0x0003
UTF-32
0x00000003
HTML Entities
Numeric

Hex

How to Type
HTML Entity

Unicode InputU+0003
Source Code Representations
C / Java
"\u0003"CSS
\0003JavaScript
"\u0003"Perl
\x{0003}Python 2
u"\u0003"Python 3
\u0003Ruby
\u{0003}Frequently Asked Questions
What is ASCII code 3?
ASCII code 3 represents the End of Text character. In hexadecimal it is 0x03, in binary 0000 0011, and in octal 3. This is a non-printable control character used for device signaling and data transmission control.
How do I type ASCII 3 on a keyboard?
Control characters are typically entered using Ctrl key combinations. For example, Ctrl+C produces ASCII 3 in most terminal emulators. You can also use the HTML entity  in web pages.