# The Useful Curiosity Desk

> The Useful Curiosity Desk is an independent explainer publication about everyday science, digital systems, animals, maps, and time. It follows questions past the catchy answer, recomputes quantities, links primary or institutional sources, and labels uncertainty where evidence is still moving.

The Useful Curiosity Desk publishes original, long-form guides about facts & explainers. Every article opens with a concise direct answer, is structured with clear headings and FAQs, and reflects mainstream expert consensus.

## Digital Systems

- [How QR Codes Work: Squares, Data, and Error Correction](https://knowmorestuff.com/how-qr-codes-work/): A QR code stores bits in a two-dimensional grid of dark and light modules.

## Everyday Science

- [Why Do Cats Purr? What Science Knows and Doesn't](https://knowmorestuff.com/why-cats-purr/): Cats purr by generating low-frequency vibration in the larynx during both inhalation and exhalation, but the exact control mechanism remains under study.
- [Why Is the Sky Blue? Rayleigh Scattering Explained](https://knowmorestuff.com/why-is-the-sky-blue/): The daytime sky looks blue mainly because air molecules Rayleigh-scatter shorter visible wavelengths more strongly than longer ones.

## Maps & Time

- [Why Time Zones Zigzag Instead of Following Longitude](https://knowmorestuff.com/why-time-zones-zigzag/): Time zones zigzag because civil time is a political and social agreement, not a direct longitude readout.

## Full text for LLMs

- [llms-full.txt](https://knowmorestuff.com/llms-full.txt): every article as plain markdown in one file
- Each article is also available as markdown at https://knowmorestuff.com/<slug>.md

## Site

- [About](https://knowmorestuff.com/about/): editorial approach and standards
- [All articles](https://knowmorestuff.com/all/)
- [Contact](https://knowmorestuff.com/contact/)