**Root cause analysis** (**RCA**) is a systematic process for identifying the fundamental underlying causes of a problem, failure, or undesirable event, with the goal of implementing corrective actions that prevent recurrence rather than merely addressing surface-level symptoms. Originating in industrial [[Quality management|quality management]] and [[Safety engineering|safety engineering]], RCA has been broadly adopted across disciplines including [[Information technology|information technology]], [[Healthcare|healthcare]], [[Manufacturing|manufacturing]], and [[Project management|project management]]. The core premise of RCA is that effective problem resolution requires understanding the causal chain that produced an undesired outcome, distinguishing between immediate causes, contributing factors, and the root cause or causes that, if addressed, would prevent similar events from recurring. RCA employs a variety of analytical techniques depending on the complexity of the problem and the context in which it is applied. The **[[5 Whys|5 Whys]]** method, developed within the [[Toyota Production System|Toyota Production System]], involves iteratively asking "why" a problem occurred until a fundamental cause is identified, and is valued for its simplicity in investigating straightforward causal chains. The **[[Ishikawa diagram|Ishikawa diagram]]** (also known as the fishbone or cause-and-effect diagram), developed by [[Kaoru Ishikawa]], organizes potential causes into structured categories—commonly people, processes, equipment, materials, environment, and management—to facilitate systematic brainstorming. **[[Fault tree analysis]]** uses a top-down [[Boolean logic|logical]] diagram to map the combinations of failures that could produce a given undesired event, and is widely used in [[Safety-critical system|safety-critical]] engineering domains. **[[Kepner–Tregoe analysis]]** provides a structured decision-analysis framework for defining a problem precisely and systematically evaluating potential causes against observable evidence. In [[IT service management|IT service management]] (ITSM), RCA is a central activity within [[Problem management|problem management]], where it is applied to recurring or high-impact [[Incident management (ITSM)|incidents]] to identify systemic causes and drive permanent resolution. ITIL defines the output of a successful RCA as a **known error** record, documenting the identified root cause and any available [[Workaround|workaround]] or fix, which is stored in the [[Known error database|known error database]] (KEDB) to support faster future incident resolution. RCA findings typically feed into [[Change management (ITSM)|change management]] processes when resolution requires modification of infrastructure or application components. The effectiveness of RCA depends heavily on the quality of [[Incident data|incident data]], the availability of accurate [[Configuration management database|CMDB]] records, and the willingness of organizations to invest in investigation beyond immediate service restoration.