The human-readable instructions that make up a program or software. Written in a high-level programming language, source code outlines the functions, operations, and structure of a software application. It’s the foundational layer that developers interact with, and thus, its quality, clarity, and security have direct implications on the functionality and security of the resulting software. Appropriate measures, such as code reviews and audits, are crucial for identifying potential vulnerabilities and ensuring the reliability of the software.