Flow is a form of an app`s logic representation. A flow begins with some message that incomes (or it may be produced inside the flow), then some logic that processes it and gives some result message further (or shows it in user interface charts, for example). So a flow is a set of connected components.
A flow consists of components and connections between them.
Tabs in the Application Builder editor called Flow as well. Each tab may carry a flow (set of connected components) or, maybe, several flows. But for a clearer view, usually, it`s better to divide your flows by tabs (which are called Flows for that reason).
Double-click a Flow tab to add its name and description.
You can make your flow more readable for other users or yourself if you organize components vertically, horizontally, by groups:
You may add a comment component onto the Workplace to make a piece of flow clearer. Double-click the comment component to add a name and description.
Divide flows by tabs or divide one flow - you may connect flows between tabs with the link in and link out components from the palette.
You may compose some logic in one tab and wire it through these components to multiple other tabs.
See link in and link out Standard components.
The clearer way to make a reusable part of logic is to create a subflow. You do the same: compose a piece of logic in a separate tab, but connect it not with links in and out, but simply creating a new "component" of it.
Open Menu (1), choose Create Subflow in Subflows (2). A new Subflow tab will appear (3). Here you can compose that piece of logic that you want to use as a subflow.
It will be available as a component on the palette - in the subflows category (4).
Double-click a Subflow tab (3) to change its name and description.
You can add inputs and outputs for your subflow at the top of its tab.
Another way to create a subflow: choose a piece of logic and click Selection to Subflow in the Subflows menu (2). A new subflow will replace this part of the flow.