Computer systems are essential for modern businesses.

Modern operating systems offer a wide variety of features.

Solar systems are composed of planets and stars.

The nervous systems control bodily functions.

Planetary systems are composed of several planets and their satellites.

The immune systems protect the body against infections.

The lymphatic systems play an important role in the immune system.

The subsystems interact to form a complete system.

Guidance systems are essential for air navigation.

Electronic bulletin systems are very useful for internal communication.