Continuous integration, continuous delivery, and continuous deployment seem to be similar to each other. Can you explain the differences between them?

"While these three terms may sound similar, there are distinct differences between them. The practice of continuous integration involves merging changes to websites back to the main branch as often as possible. This avoids having to merge their changes into the release branch just before it is released. Continuous delivery is an extension of continuous integration that releases changes quickly in a sustainable way. This involves automating the testing and release processes so the application can be deployed at any time. Continuous deployment is the next step. This practice passes changes during all stages of production directly to the websites, with no intervention. Only failure of an automated test will prevent a change from being deployed."