User Accounts

Linux kernel authenticated users to access files and applications.
while each user is identified by a unique integer (the user id or UID), a separate database associates a username with each UID.

Types of Accounts

By default, Linux distinguishes between several account types in order to isolate processes and workloads.
Linux has fourtypes of accounts:

  • root
  • System
  • Normal
  • Network

For a safe working env, it is advised to grant minimum privileges possible and necessary to accounts, and remove inactive accounts.
The last utiltiy, which shows the last time each user logged into the system, can be used to help identify potentially inactive accounts which are candidates for system removal.