Other than root , every other user has limited access to files and directories. Always use your machine as a normal user. Login as root only to do system administration. This will save you from the destructive power that the root user has. Here we will show how to manually and automatically create new users.
Users are also divided into sets, called groups .
A user may belong to several groups and there can be as many groups on the system as you like. Each group is defined by a list of users that are part of that set. In addition each user has a group of the same name, to which only he belongs. Each file on a system is owned by a particular user and also owned by a particular group. To change the ownership of the file simply use the chown , change ownerships , command as follows.