This chapter is about the user environment. You will learn how to set up a user account, which is an important task, even if you are not a computer administrator. You will also learn about the way authentication is handled using the PAM (pluggable authentication module) and nsswitch systems, as well as explore the configuration files that contain the definition of the working environment for your users. For instance, you will see how to provide a user with default settings by using the /etc/profile file and all related files. Also, you will get a look at the sudo mechanism, which allows you to perform administration tasks without needing to log in as root.