How you manage application development depends on how large the application is you will be creating, and the number of developers you will have working on the project.
Small applications with only one or two developers can be managed manually. You can perform development in a single dictionary, making regular backups to create an archive of changes. This allows you to revert back to a previous version if necessary.
If you will be creating a large application, or will have many developers working on your project, we strongly recommend that you implement source code control to manage the development process. Source code control allows many developers to work on a single dictionary without having to worry about concurrency issues (users trying to change the same resources at the same time). It also provides revision management, allowing you to maintain all of the revisions of your product. You can easily re-create any version of your product at any time. Refer to Source Code Control for a complete description of how to use source code control when developing applications with Dexterity.