What is defined as the modification of a software product after its initial delivery?

The modification of a software product after its initial delivery is referred to as maintenance. This phase involves activities such as fixing defects, enhancing performance, or adding new features to meet user needs or accommodate changes in the environment in which the software operates. Maintenance ensures that the software continues to function effectively and remains relevant over time. It is a critical aspect of the software lifecycle, often accounting for a significant portion of the total cost of ownership of software systems.

In contrast, development refers to the process of creating software from scratch, including design, coding, and testing. Deployment typically involves the installation and configuration of the software for use by end-users after development is complete. Optimization focuses on refining the software to improve its performance or efficiency but does not cover the broader scope of ongoing modifications that maintenance addresses.