ASCII Table

ASCII (American Standard Code for Information Interchange) is a character encoding standard that assigns numeric values to 128 characters. It was first published in 1963 and includes control characters (0-31), printable characters (32-126), and the DEL character (127). ASCII forms the foundation of virtually all modern character encodings, including UTF-8.

ASCII defines 128 characters using 7 bits, covering only English letters, digits, punctuation, and control characters. Unicode is a superset that defines over 149,000 characters covering virtually every writing system in the world. The first 128 Unicode code points (U+0000 to U+007F) are identical to ASCII. UTF-8, the most common Unicode encoding on the web, is fully backward-compatible with ASCII.

Control characters (codes 0-31 and 127) are non-printable characters originally designed to control hardware devices like printers and teleprinters. Common examples include NUL (0), TAB (9), LF/Line Feed (10), CR/Carriage Return (13), and ESC/Escape (27). Many remain important today in network protocols, terminal emulation, and file formats. For example, HTTP headers are separated by CR+LF (13+10).

ASCII is fundamental in cybersecurity for analyzing network protocols, examining malware strings, understanding encoding-based attacks (null byte injection, CRLF injection, directory traversal), reverse engineering binary files with hex editors, and parsing log files. Security analysts frequently reference ASCII decimal and hex values when working with packet captures, shellcode, and exploit payloads.