Convert ASCII Characters to Binary

ASCII (American Standard Code for Information Interchange) assigns a 7-bit binary number to 128 characters including letters, digits, punctuation, and control characters. Extended ASCII uses 8 bits for 256 characters.

Step-by-step example — converting "Hello" to binary:

Look up each character's ASCII code and convert to 8-bit binary:

• H = 72 = 01001000
• e = 101 = 01100101
• l = 108 = 01101100
• l = 108 = 01101100
• o = 111 = 01101111

Binary: 01001000 01100101 01101100 01101100 01101111

Key ASCII ranges to memorize:

Range	Characters	Decimal	Binary Pattern
Control	NUL to US	0-31	000xxxxx
Digits	0-9	48-57	0011xxxx
Upper	A-Z	65-90	010xxxxx
Lower	a-z	97-122	011xxxxx

Useful patterns:

• The difference between uppercase and lowercase is exactly 32 (one bit flip): A (65, 01000001) vs a (97, 01100001). Bit 5 (value 32) is the case bit.
• Digits 0-9 are offset by 48 from their numeric value: '0' = 48, '5' = 53.
• The space character is 32 (00100000), which is why it comes before all printable characters in sorting.

ASCII in modern computing:

ASCII is the foundation of UTF-8 encoding. The first 128 UTF-8 characters are identical to ASCII, meaning any ASCII text is automatically valid UTF-8. This backward compatibility is one reason UTF-8 became the dominant text encoding on the web. Understanding the binary representation of ASCII characters is crucial for text processing, data serialization, protocol analysis, and low-level string manipulation.