Source code is a series of commands, written in a human-readable computer language, that instructs a computer on how to execute a task. It's the first stage in software development, and it's transformed into executable code by a compiler or interpreter.
The source code contains the logic that controls how an application behaves. It's usually written in high-level programming languages that humans can understand. Examples include C++, Python, Java, and JavaScript. The source code for a project is typically stored in a source code repository, such as GitHub.
Open-source software projects share their source code publicly, allowing anyone to view, use, modify, and distribute the project's code. This open collaboration can lead to more robust and reliable software because it's continually scrutinized and improved by the community.