System Administration involves managing and maintaining computer systems and networks. It includes tasks like configuring hardware and software, ensuring system security, performing backups, and troubleshooting issues. System administrators, or sysadmins, play a crucial role in ensuring the reliability and performance of IT infrastructure. They manage servers, user accounts, and network resources, ensuring that businesses can operate smoothly. System administrators also implement updates, patches, and security measures to protect against cyber threats and keep systems up-to-date.