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More advanced organizations may have a central login server, such as 
Active 
Directory
 (
AD
) or standard LDAP. There are also others aside from those, as well. 
In this book, we won't cover those technologies, but just keep in mind that central 
authentication servers are a possibility for your organization, should you choose to 
explore them.
The most powerful user of all, though, is 
root
. This special user gives us the most 
control, but as you'll see in the next section, that comes with risks.
Understanding when to use root
In the last chapter, we set up our very own Ubuntu Server installation. During the 
installation process, we were instructed to create a user account to act as a system 
administrator. So, at this point, we should have at least two users on our server. 
We have the aforementioned administrative user, as well as 
root
. We can certainly 
create additional user accounts with varying levels of access (and we will do so in 
this chapter), but before we get to that, some discussion is in order regarding the 
administrator account you created, as well as the 
root
 user that was created for you.
The 
root
 user account exists on all Linux distributions and is the most powerful 
user account on the planet. The 
root
 user account can be used to do anything within 
your server, and I do mean 
anything
. Want to create files and directories virtually 
anywhere on the filesystem? Want to install software? These processes are easily 
performed with 
root
. The 
root
 account can even be used to destroy your entire 
installation with one typo or ill-conceived command: if you instruct 
root
 to delete 
all the files on your entire hard disk, it won't hesitate to do so. It's always assumed 
on a Linux system that if you are using 
root
, you are doing so because you know 
what you are doing. So, there's often not so much as a confirmation prompt while 
executing any command as 
root
. It will simply do as instructed, for better or worse.
It's for this reason that every Linux distribution I've ever used states, or at least 
highly recommends, that you should create a standard user during the installation 
process. It's generally recommended in the Linux community for an administrator 
to have their own account and then switch to 
root
 whenever a task comes up that 
requires 
root
 privileges to complete. This approach is less likely to destroy your 
server with an accidental typo or bad command while you're logged in as 
root
. Some 
administrators will strictly use 
root
 at all times without any issue, but again, it's 
recommended to use 
root
 only when you have to. 

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Managing Users and Permissions