Software maintenance and evolution continues to play a vital role in the development of software systems. It is widely acknowledged that the majority of development effort, and thereby expenditure, is allocated to postinitial release activity. This activity, which takes place after the software has seen its first release, is known as software maintenance (or software evolution).
Linos, Panos K., "Guest Editorial: Special Issue on Software, Maintenance and Evolution" (2005). Scholarship and Professional Work - LAS. Paper 89.