A cluster is a group of machines that work together as a single system to ensure that applications and resources are available at all times.
The computers are physically connected by cables and programmatically connected by cluster software. These connections allow computers to use fail over and load balancing, which is not possible with a stand-alone computer.
The machines are managed as a single system using cluster software, which provides a way to support fault-tolerance, high-availability, scalability, and so on.
