ASCII
7-bit encoding mapping 128 characters to numbers.
ASCII (American Standard Code for Information Interchange) is a character encoding standard published in 1963 that maps 128 characters to 7-bit binary numbers (0-127).
Character ranges:
- 0-31: Control characters (non-printing)
- 32-126: Printable characters (95 characters)
- 48-57: Digits 0-9
- 65-90: Uppercase A-Z
- 97-122: Lowercase a-z
- 127: DEL (delete)
The first 128 Unicode characters are identical to ASCII for backward compatibility.
graph LR
Center["ASCII"]:::main
Rel_unicode["unicode"]:::related -.-> Center
click Rel_unicode "/terms/unicode"
Rel_binary["binary"]:::related -.-> Center
click Rel_binary "/terms/binary"
classDef main fill:#7c3aed,stroke:#8b5cf6,stroke-width:2px,color:white,font-weight:bold,rx:5,ry:5;
classDef pre fill:#0f172a,stroke:#3b82f6,color:#94a3b8,rx:5,ry:5;
classDef child fill:#0f172a,stroke:#10b981,color:#94a3b8,rx:5,ry:5;
classDef related fill:#0f172a,stroke:#8b5cf6,stroke-dasharray: 5 5,color:#94a3b8,rx:5,ry:5;
linkStyle default stroke:#4b5563,stroke-width:2px;
🧠 Knowledge Check
🧒 Explain Like I'm 5
Computers only understand numbers. ASCII is like a secret code that says 'A=65, B=66, C=67...' so computers know which letter you mean when you type!
🤓 Expert Deep Dive
Control characters (0x00-0x1F) originated from teletype commands. CR+LF (0x0D+0x0A) vs LF (0x0A) line endings differ across OS. EBCDIC (IBM) competed with ASCII early on. Base64 encoding uses 64 ASCII characters to encode binary data.