Today the dependability of the communications infrastructure and the applications flowing over networks is more important than ever. Users rapidly become dependent on new networked services to conduct their personal and professional lives. Users expect new, innovative distributed services to be delivered on demand and without interruption. Understanding Service Availability article tells that communications and enterprise computing industries are under enormous pressure to revamp networks and applications to accommodate explosive growth and emerging technologies. A key requirement to deploy a highly available system is that it must provide uninterrupted service even in the event of hardware or software failures. Historically, Network Equipment Providers (NEPs) have designed and built such systems from the ground up, using the specialized, in-house expertise developed over decades. The key principles of Service Availability extend beyond the reactions to a failure, meaning availability engineering moves into diagnosis and correction. The Service Availability Forum is a consortium that develops, publishes, educates on and promotes open specifications for carrier-grade and mission-critical systems.