The CI shows the entire team that the tests are passing, and doesn't require other devs to pull it and run the tests themselves. It prevents devs from accidenta

The CI shows the entire team that the tests are passing, and doesn't require other devs to pull it and run the tests themselves. It prevents devs from accidentally forgetting to run tests, or thinking "This is just a typo fix, it shouldnt break any tests". Tests might also run on multiple platforms/os's/architectures/versions, etc. The CD ensures that the code is only deployed after all tests passed, it was approved, merged, and ensures a deploy isn't skipped accidentally. Depending on what your doing it could take a while to fully build new binaries, build for multiple platforms/versions/architectures, etc.