--- title: "Character Sets: Storing Text as Numbers" description: "Every character has an agreed number, and the text on screen is those numbers drawn by a font. A shared standard is what lets two machines read the same file, and one byte per character stopped being " canonical: https://lightmysky.com/learn/computing/character-sets-storing-text-as-numbers-mt_839VNNZlp2 source: https://lightmysky.com/learn/computing/character-sets-storing-text-as-numbers-mt_839VNNZlp2.md retrieved: 2026-09-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Character Sets: Storing Text as Numbers Every character has an agreed number, and the text on screen is those numbers drawn by a font. A shared standard is what lets two machines read the same file, and one byte per character stopped being enough. Subject: Computing · Area: Computer Systems · Ages 14 to 15 Page: https://lightmysky.com/learn/computing/character-sets-storing-text-as-numbers-mt_839VNNZlp2 ## Ready when they can - Explain what a character set is and why both machines have to use the same one - Work out the code of a letter given the code of another letter in the same run - Say why scripts beyond Latin, and emoji, needed a larger standard ## Lesson: Letters are numbers in disguise Computers store letters as numbers. A character set is the agreed table that pairs each letter, digit and symbol with a number, and the font draws the number back as a shape you can read. Both machines must use the same table, or the numbers turn back into the wrong text. **Example.** Early tables were small: one well-known table gives the common letters codes under 128, with A at 65. Since letters in a run sit side by side, B is 66 and C is 67. One byte per character was simple and fast. One byte stopped being enough when scripts beyond Latin and emoji needed far more codes. The world moved to wider standards that hold hundreds of thousands of characters. The same bits can mean a letter, a colour shade or part of a sound, so the agreed code decides the meaning. **Tip.** When text opens as odd symbols, suspect the table first. A mismatch of character sets is the classic cause. **Recap.** A text file is a file of numbers, readable only with the matching character table. ## Practice 8 questions on this page, each with its working shown. ## Needs first - [An Agreed Code: How the Same Bits Mean Letters or Colours](https://lightmysky.com/learn/computing/an-agreed-code-how-the-same-bits-mean-letters-or-colours-mt_IQY-PHtZVZ) - [Hexadecimal as Binary Shorthand](https://lightmysky.com/learn/computing/hexadecimal-as-binary-shorthand-mt_OV6PHdnU6N) ## Opens up - [Bitmap Images: Pixels, Resolution and Colour Depth](https://lightmysky.com/learn/computing/bitmap-images-pixels-resolution-and-colour-depth-mt_-Tr40QK8sN)