Procedural audio is sound qua process, as opposed to sound qua product. Behind this statement lies a veritable adventure into semiotics, mathematics, computer science, signal processing and music. Let us reformulate our definition in verbose but more precise modern terms before moving on. Procedural audio is non-linear, often synthetic sound, created in real time according to a set of programmatic rules and live input. To further define it let's explain it in terms of linear, recorded, interactive, adaptive, sequenced, synthetic, generative and AI audio. Let's also analyse some other phrases like algorithmic composition and stochastic music. By doing so, we may reach an understanding of why procedural audio is so powerful and important.