What is uptime and what guarantee is good?
Uptime is the percentage of time your website is reachable. 99.9% is the standard and means at most about 9 hours of downtime a year. Distrust promises of 100%, and look instead at what a provider does when things break: communication, credits, and recovery speed.
No server runs flawlessly forever; maintenance, hardware failures, and network issues are part of the job. Uptime guarantees express how much interruption to expect. 99.9% sounds near-perfect but allows almost 9 hours a year; 99.99% under one hour. For a hobby blog that difference is trivial; for a store, every hour is lost revenue.
The guarantee itself is mostly a promise about credits: miss the percentage and you typically get part of a month's fee back, which rarely covers real damage. So look beyond the number. Does the provider run a public status page? Does it communicate openly during incidents? Premium parties like Kinsta monitor your site continuously and fix issues before you notice.
Want to verify it yourself? Point a free monitor like UptimeRobot at your site; then you will know about an outage before your visitors do, and you will have your own data at renewal time.