Troubleshooting is problem solving technique by which we repair failed products or processes on a machine or a system. It is a logical, systematic search for the source of a problem in order to solve it. Troubleshooting is needed to identify the symptoms. troubleshooting is applied to something that has suddenly stopped working, since its previously working state forms the expectations about its continued behavior.

A system can be described in terms of its expected, desired or intended behavior (usually, for artificial systems, its purpose). Events or inputs to the system are expected to generate specific results or outputs. (For example, selecting the "print" option from various computer applications is intended to result in a hardcopy emerging from some specific device). Any unexpected or undesirable behavior is a symptom. Troubleshooting is the process of isolating the specific cause or causes of the symptom. Frequently the symptom is a failure of the product or process to produce any results.