Meaning
A period of time during which a computer system, server, or software application is unavailable or offline.
Three examples from work
Maintenance planning
DevOpsWill the database upgrade require any scheduled downtime?
DBAWe can perform a zero-downtime rolling switchover with zero disruption to active users.
Incident impact
CFOWhat was the estimated business cost of yesterday's forty-minute downtime?
PMWe lost roughly fifteen thousand dollars in uncompleted checkout orders.
Status page update
Support LeadWe should post an incident update on the public status page explaining the downtime.
LeadDrafting the post-mortem explanation now.
Distinguish between 'scheduled downtime' (planned maintenance) and 'unscheduled downtime' (unexpected outages).