• Simple Command Expansion: How Bash expands simple commands before executing them. • Command Search and Execution: How Bash finds commands and runs them. • Command Execution Environment: The environment in which Bash executes commands that are not shell builtins. • Environment: The environment given to a command. • Exit Status: The status returned by commands and how Bash interprets it. • Signals: What happens when Bash or a command it runs receives a signal.