Source code (sometimes just called “source” or “code”) consists of human-readable computer instructions written by programmers. It’s the original form of a computer program before it gets converted into a format that computers can execute directly.

Here’s an example of some source code written in Python:

When programmers talk about “reading the source” or “checking the source code,” they mean examining these original, human-readable program files. The source code represents the authoritative version of how a program works and contains all the implementation details of its functionality.