What does continuous integration primarily focus on?

Continuous integration primarily focuses on integrating or merging the work of the development team. This practice involves frequently combining individual contributions to a shared repository to ensure that all code changes work together seamlessly. By emphasizing the integration process, teams can detect errors and conflicts early in the development cycle, which helps in maintaining a consistent codebase and facilitates collaboration among team members. This approach not only enhances code quality but also accelerates the overall development process, allowing teams to respond more rapidly to changes and challenges.

The other choices relate to different aspects of software development but do not capture the essence of continuous integration. Automating user notifications pertains to user engagement rather than integration practices. Reducing deployment time is more aligned with continuous delivery or deployment strategies, while improving user interface design focuses on the visual aspects of applications rather than the back-end integration processes.