The UN Evaluation Group (UNEG) defines evaluation as follows:
“….an assessment, as systematic and impartial as possible of an activity, project, programme, strategy, policy, theme, sector, operational area or institutional performance. It focuses on expected and achieved accomplishments examining the results chain, processes, contextual factors and causality, in order to understand achievements or the lack thereof. It aims at determining the relevance, impact, effectiveness, efficiency and sustainability of the interventions and contributions of the organizations of the UN system.”
In simpler terms, evaluation is intended to provide accountability for achieving results from the use of resources, and to facilitate learning from experience in ways that can be put into practical use. Furthermore, evaluation should influence policy and operational decisions.