# Rene Descartes and Computer Science — Liran Tal

where do you think the idea of using variables in computer science came from?

Canonical: https://lirantal.com/blog/2007-11-12

We use variables to represent unknown values in mathematical problems every day. Descartes, who lived during the 16th – 17th century came up with the idea to use the lower letters of the English alphabet as variables in equations (such as `x, y, z`) and the upper letters of the alphabet as constants (`a, b, c`).

Reference: [http://en.wikipedia.org/wiki/Ren%C3%A9\_Descartes](http://en.wikipedia.org/wiki/Ren%C3%A9_Descartes)

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Liran Tal is the author of the book [Node.js Secure Coding: Defending Against Command Injection Vulnerabilities](https://www.nodejs-security.com/)

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