Glossary
Status page & incident glossary
Plain-English definitions of the terms you'll meet when running a status page and handling incidents.
Status page · Component · Incident · Incident update · Scheduled maintenance · Maintenance window · Operational · Degraded performance · Partial outage · Major outage · Uptime · Downtime · SLA · SLO · SLI · Error budget · MTTD · MTTA · MTTR · MTBF · Incident severity · Postmortem · Root cause analysis · Subscriber · Endpoint monitoring · Private status page · Status badge
Status page
A public or private web page that shows the current health of a product's services, lists active incidents and scheduled maintenance, and lets people subscribe to updates.
Component
One part of your product shown on a status page, such as Website, API or Payments. Each component has its own status and uptime history. Statusentry calls these services.
Incident
An unplanned event that disrupts or degrades a service. On a status page it moves through Investigating, Identified, Monitoring and Resolved.
Incident update
A timestamped message posted to an incident explaining what's affected, what you're doing and when the next update will come.
Scheduled maintenance
Planned work announced in advance, with a start and end time and the expected impact on users.
Maintenance window
The agreed period during which scheduled maintenance happens, often at a low-traffic time and often excluded from SLA calculations.
Operational
The status of a component that is working normally.
Degraded performance
A component works but is slower or less reliable than usual.
Partial outage
A component is unavailable for some users, regions or features, but not all.
Major outage
A component is unavailable for most or all users.
Uptime
The share of time a service is available, usually shown as a percentage over a period such as 30 or 90 days.
Downtime
Time during which a service is unavailable to users.
SLA (service level agreement)
A promise to customers about availability or performance, such as 99.9% monthly uptime, often with service credits if it isn't met.
SLO (service level objective)
An internal reliability target, usually stricter than the SLA, that a team aims to meet.
SLI (service level indicator)
The metric used to measure an SLO, for example the percentage of successful requests.
Error budget
The amount of unreliability an SLO allows. A 99.9% SLO leaves a 0.1% error budget, about 43 minutes a month.
MTTD (mean time to detect)
The average time between a problem starting and the team finding out about it.
MTTA (mean time to acknowledge)
The average time between an alert and someone starting to work on it.
MTTR (mean time to resolve)
The average time from the start of an incident to full recovery. Sometimes used for mean time to repair or recover.
MTBF (mean time between failures)
The average time a system runs between incidents.
Incident severity
A level, such as SEV1 to SEV3, that ranks how serious an incident is and decides who responds and how quickly.
Postmortem
A written review after an incident covering what happened, why, and what will change. Also called a post-incident review.
Root cause analysis (RCA)
The process of finding the underlying cause of an incident rather than only its symptoms.
Subscriber
Someone who signs up on a status page to receive incident and maintenance notifications by email, Slack, webhook or SMS.
Endpoint monitoring
Automated checks that request a URL at set intervals and alert you when it fails or responds slowly.
Private status page
A status page visible only to signed-in users, such as employees or specific customers.
Status badge
A small embeddable widget that shows your current status on another site, such as your app or docs.
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