Which of the following is not a stage of system development cycle?

The system development life cycle describes the recognised stages a new computer system passes through, from identifying a need to putting the finished system into use. The commonly taught stages include analysis, design, development or coding, test running, and implementation.

• Design: creating the plan and structure for how the new system will work, based on the requirements gathered earlier.
• Test running: checking the developed system for errors and confirming it works correctly before it is put into full use.
• Implementation: putting the completed and tested system into actual operation, including installing it and training users.

"Observation" is not one of the formally named stages of the system development life cycle. While observing how a system performs can happen informally during testing or after implementation, it is not itself a distinct, named stage in the standard model; it is instead an activity that can occur within stages like analysis or evaluation, rather than a separate, defined phase.

Exam reminder: memorise the standard named stages of the system development life cycle (typically analysis, design, development, testing, and implementation) so that an unfamiliar or generic term like "observation" can be quickly identified as not belonging to the list.