Layout
Layouts contain the whole static (X)HTML markup of a clients frontend page.
Each place, which later should have dynamic content, such as the whole content area, navigation or similar things, you can define so called container . Each container is a representation of a module, which is later assigned in a template to the specific layout.
Layouts are not shared with other clients and saved in the clients data directory in the subfolder layouts.
Changes to a layout in filesystem may require synchronizing all layouts in backend.