Again, Linux is a highly secure operating system that depends on strict file permissions dictating which users and groups can access them. Let’s look at some classifications of users that are found on a Linux system.
Admin or Non-admin?
A Linux user is either an administrator or non-administrator. The administrator is a superuser (or root user) with full control over the entire system. With that in mind, it is important to ensure that only a very limited number of folks have read and write permissions on all the files in the entire system. In contrast, a non-administrator by default has limited (or no) access to certain system/configuration files.
A majority of the accounts will be non-administrators. These users can be divided into two subtypes: normal user or system user. Normal users are real people. The individual is given a user account for login and limited access to computer applications, files, and resources.
A system user is typically a non-human or computer-generated account. System users are created to run a specific program or process/daemon such as a web server or backup program. This type of “user” is limited in control and is assigned only enough access to manage its particular process.