The document provides an introduction to system administration, including defining system administration as the management of computers, hardware, software, operating systems, applications, networks, and users. It describes the duties of a system administrator such as applying updates, installing/configuring hardware/software, managing user accounts, performing backups and security tasks. The document also discusses different types of administrators including database, network, security, and web administrators. It provides an overview of common operating systems used for administration like Windows, Unix, Linux distributions.