System administrator

A system administrator describes the role of a person whose job includes maintenance duties for the long-term support of a computer system.

Typical daily tasks for a system administrator include:

password reset
printer queue troubleshooting
userid add/modify/delete
troubleshooting, and answering questions
perform backup and restore operations of files

These more infrequent tasks are also an important part of a System Administrator's job:

Operating System configuration changes
software updates, for the OS or the application(s) it runs
hardware changes

Typical responsibilities of a System Administrator:

documenting the configuration of the system
keep the system operating
maintain the security of the system
keep the application running
participate in most changes to the system
own the passwords to the administrative userids

To call yourself a System Administrator (SysAdmin), is to sharply define yourself as different from the following roles commonly found in the IT industry:

DBA
Application Analyst
Programmer
Network Specialist
System Architect