Text in Computers

How is textual data represented in a computer’s memory.

Published

October 2, 2025

Modified

March 14, 2026

💻 Text in Computers 📝

In early years, different computer companies applied the binary system in their own way. The word “cat” would be encoded in binary different on different brands of computers. This made life difficult in terms of being able to transfer data from one system to another.

🅰️ ASCII

  • ASCII (American Standard Code for Information Interchange)
    • Originally a 7-bit code with 128 combinations
  • Later expanded to 8 bits (256 combinations) — called Extended ASCII-8
    • Note: When people say “ASCII,” they usually mean Extended ASCII-8
  • Why 8 bits?
    • Each character fits perfectly into 1 byte
  • Example:
    • "CAT" → 0100 0011 0100 0001 0101 0100
    • "cat" → 0110 0011 0110 0001 0111 0100

📊 ASCII-8: Table of Characters

Information above comes from ASCII Values Alphabets

🌐 Unicode

ASCII works well for English and other Latin-based languages, but many languages need more than 256 characters 🌏. For example:
- 🇨🇳 Chinese: 汉字 (China)
- 🇯🇵 Japanese: 漢字 (Japan)
- 🇷🇺 Cyrillic: Кири́ллица (Russia)
- 🇮🇳 Gujarati: ગુજરાતી (India)
- 🇵🇰 Urdu: اردو (Pakistan)

To solve this, we use Unicode, which comes in several versions that use different numbers of bits to store data. The most common format is UTF-8, an 8-bit variable-width encoding that maximizes compatibility with ASCII while allowing expansion up to 48 bits for larger character sets. UTF-16 uses 16-bit variable-width encoding and can expand to 32 bits, while UTF-32 uses a fixed-width 32-bit system where every character takes exactly 32 bits. With over 60,000 characters supported in UTF-16 and more than 4 billion in UTF-32, Unicode can represent virtually every character from every language on the planet. For instance, the code point U+007A represents the Latin small letter z (007A in UTF-16), while U+6C34 represents the Chinese character for water (水), stored as 6C34 in UTF-16. Since the numbers used in UTF-16 and UTF-32 can be extremely large, it is not convenient to write them in binary, which is why we often use hexadecimal instead.

Information adapted from Wikibooks: ASCII and Unicode — you can find more detailed explanations there.

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