Most of the time, you'll be creating published versions to share with other artists who are collaborating with you on a project, and to save different ideas for a shot. For example, you can publish several color correction possibilities to show a client. When the client decides on one, you can resume working on the result that was chosen. If the client changes their mind later, it is easy to switch to a different result.
There are several concepts that are fundamental to understanding compositing in Toxik: intermediate results, publishing results, and versions of compositions.