This document is the user’s manual for the CompCert C verified compiler. It is organized as follows: Chapter 1 gives an overview of the CompCert C compiler and of the formal verification of compilers. Chapter 2 explains how to install CompCert C. Chapter 3 explains how to use the CompCert C compiler. Chapter 4 explains how to use the CompCert C reference interpreter. Chapter 5 describes the subset of the ISO C99 language that is implemented by CompCert. Chapter 6 describes the supported language extensions: pragmas, attributes, built-in functions.