Summative assessment demonstrates the extent of a learner's success in meeting the assessment criteria used to gauge the intended learning outcomes of a module or programme, and which contributes to the final mark given for the module. It is normally, though not always, used at the end of a unit of teaching. Summative assessment is used to quantify achievement, to reward achievement, to provide data for selection (to the next stage in education or to employment). For all these reasons the validity and reliability of summative assessment are of the greatest importance.