Data availability is the ability to access information and services when they are needed. In cybersecurity, it is one of the core goals alongside confidentiality and integrity. A system can be perfectly protected against unauthorized reading, yet still fail the security mission if users cannot reach data, applications, or critical services on time.
Availability matters because many attacks target disruption rather than theft. Denial-of-service traffic, ransomware, destructive malware, and supply-chain outages can all make systems unusable. The same risk can also come from non-malicious causes such as power loss, heat stress, hardware failure, or severe weather. Defenders protect availability with redundancy, backups, failover systems, capacity planning, monitoring, and disaster recovery procedures. In risk management standards like ISO/IEC 27001:2022, availability planning is part of keeping services resilient under both cyber and environmental pressure.