Fault tolerance or graceful degradation is a feature that allows the system (often computer-based) to continue to work correctly if the bug (or one or more months), or some of its components. If the operating loss of quality at all, the reduction is proportional to the severity of failure than naively designed a system in which even a small error can cause a complete collapse. Fault-tolerance is particularly sought after high-availability, or life-critical systems. Fault tolerance is not only a property of individual machines, but can also characterize the rules by which they interact. For example, the Transmission Control Protocol (TCP) is designed to allow secure communication of the two channels in a packet switched network, even in the presence of communication channels that are imperfect or overloaded. To do so, require the ends of the communication to expect packet loss, duplication, reorganization and corruption, so that these conditions do not damage data integrity, and only reduce the flow of a proportional amount.
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