Reliability and availability are two of the most important, and often confused, maintenance KPIs.

The difference is crucial: - **Reliability** is about how *infrequently* a machine fails.

It's a measure of failure frequency.

A highly reliable vehicle is one that rarely breaks down.

- **Availability** is about whether the machine is *ready to work* when you need it.

It's a measure of uptime.

You can have an unreliable machine with high availability if its failures are very minor and repairs are extremely fast.

Conversely, you could have a very reliable machine that rarely fails, but when it does, the repair takes weeks, resulting in poor availability.

Reliability is commonly measured by Mean Time Between Failures (MTBF).

A higher MTBF means the equipment is more reliable.

Improving reliability is a primary goal of preventive and predictive maintenance strategies.

By preventing failures from occurring in the first place, you directly increase the reliability of the equipment, which in turn is a major driver of increased availability.