Some feature sets of 4D are not part of the core 4D package and are instead separte modular packages that can be added or removed from 4D as needed. When installed 4D components and modules are also included with the correct versioning specific to the build of 4D.
These components and modules are not always needed for some applications and as such can be excluded during the build process. When building an application, the Build Application window has a tab that allows the components and modules to be included or excluded with the build.
By default, a new applicaiton will include all of the components and modules. To keep the size of the resulting built application smaller and to reduce the size of the files needed for a client to sync to the server it would be beneficial to only include components that are being used.