ASCII Values Alphabets ( A-Z, a-z & Special Character Table )

ASCII (American Standard Code for Information Interchange) is a character encoding standard that assigns unique numeric values to letters, digits, punctuation marks and symbols. Since computers work only with binary data (0s and 1s), ASCII acts as a bridge by converting human-readable characters into machine-readable numbers.

• Each character is assigned a unique ASCII value ranging from 0 to 127.
• Uppercase letters, lowercase letters, digits and symbols all have different ASCII values.
• Example: 'A' = 65, 'a' = 97, '0' = 48

How do Computers Use ASCII to Understand Human Text

When you type a message like “Hello!”, each character is converted into its ASCII value:

• H → 72
• e → 101
• l → 108
• l → 108
• o → 111
• ! → 33

This process continues as follows:

• Each ASCII value is converted into binary (0s and 1s), which is the language computers and networks understand.
• The binary data is then transmitted digitally through communication channels such as the internet, cables or wireless signals.
• The receiving device decodes the binary data back into ASCII values.
• Finally, those ASCII values are translated back into readable characters, displaying the original text exactly as it was sent.

What’s Before 33 and Beyond 126 in ASCII

ASCII characters are divided into distinct ranges, each designed for a specific purpose that is displaying text, controlling formatting or supporting extended symbols.

1. Printable Characters (32–126)

• Begin with the space character (32) and end with the tilde (~) character (126).
• Include uppercase and lowercase letters, digits, punctuation marks and commonly used symbols.
• Represent the most frequently used characters in everyday text.

2. Control Characters (0–31 and 127)

• Reserved for text formatting and data transmission control.
• Not printable or visible on screen.
• Common examples include: LF (10) – Line Feed, CR (13) – Carriage Return, TAB (9) – Horizontal Tab, DEL (127) – Delete
• Widely used in early telecommunication systems, terminals and printers.

3. Values Beyond 127 (Extended ASCII)

• Values from 128 to 255 are commonly referred to as Extended ASCII.
• Extended ASCII is not a single standardized encoding.
• Different systems (such as Windows-1252 and ISO-8859-1) assign different characters to these values.
• This lack of standardization led to compatibility issues, which ultimately contributed to the development of Unicode.

Difference Between ASCII and Unicode