A system administrator (sysadmin) is an IT professional that maintains and configures computer systems and networks. They are responsible for ensuring that IT systems are running smoothly, that software is up-to-date and secure, and that hardware is functioning properly.
The responsibilities of a system administrator vary depending on the organization but may include tasks such as setting up and configuring servers, managing user accounts and permissions, monitoring system performance, troubleshooting issues, and creating backups and disaster recovery plans.