What is the process called when software is modified post-delivery to correct issues or enhance performance?

The process of modifying software after its delivery to address issues or improve performance is known as maintenance. This encompasses a variety of activities aimed at ensuring that the software remains functional and relevant over time. Maintenance typically involves bug fixes, performance improvements, and updates to keep the software aligned with user needs and technological advancements.

In the context of software life cycles, maintenance is crucial as it allows developers to respond to feedback, fix defects that were not identified during the initial development phase, and implement enhancements that could improve usability or efficiency. Maintenance ensures the longevity of the software and helps to guarantee that it continues to meet its users' needs.

In contrast, the other options do not accurately describe this post-delivery modification process. Development refers to the initial creation of software, refactoring pertains to restructuring existing code to improve its readability or performance without altering its external behavior, and upgrading typically means replacing an existing version of software with a newer version rather than ongoing modifications.