The process of modifying a system or component after delivery to correct faults, improve performance or other attributes, or adapt to a changed environment.
ISO/IEC/IEEE. 2010. Systems and Software Engineering -- Vocabulary (SEVocab) Geneva, Switzerland: International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC)/Institute of Electrical and Electronic Engineers (IEEE) 2009 ISO/IEC/IEEE 24765:2010 [database online]. Accessed on 11 September 2012. Available from http://pascal.computer.org/sev_display/index.action.