What defines a mission-critical system?

A mission-critical system is fundamentally defined by its importance to business operations. Such systems are vital for ensuring that essential functions of an organization can be carried out effectively and without interruption. They directly impact the organization's ability to serve its customers, maintain revenue flow, and uphold its reputation. When considering mission-critical systems, the focus is on their role in supporting core business processes; their failure could result in serious consequences such as financial loss, operational disruption, or a negative impact on customer trust.

The emphasis is not on the need for ongoing maintenance, which applies to many systems, nor on their design for public safety, which is a specific use case. Additionally, while having no backup options may suggest a higher risk, it does not inherently define a mission-critical system, as many critical systems have redundancy and failover mechanisms in place to ensure continuity. The defining feature of being essential to business function is what sets mission-critical systems apart.