In a multi-user business, System Administrators are in charge of the administration, management, and support of the IT infrastructure.
Depending on the size of the business or the breadth of work required, responsibilities within the area of IT systems administration might be split among multiple job titles. For example, in a large company, the responsibilities of a database administrator (DBA), security administrator, and network administrator may be different, while at a smaller company, a single sysadmin may do all of these tasks.