A Destination is where the data you send through the Data Manager will end up once processed. There are four Internal Destinations, and a steadily-growing number of External Destinations
Internal Destinations
Here you can see an example of a Destinations overview. At the bottom are the four Internal Destination, available by default for all users - Search, Merchandising, Recommendation Engine and the Customer Data Platform. These cannot be edited, but each has a status-line showing how many Dataflows and Schemas currently connect to it. By moving the mouse over one of the numbers, a complete list can been seen.
This can provide a handy overview of where exactly your various Dataflows are funneling your data!
External Destinations
Above the Internal Destinations, you'll find any External Destinations you have created.
Like the Internal Destinations, these will feature an information-bar showing the Dataflows and Schemas connected to it. However, unlike Internal Destinations, these can be Edited and - if they are not currently connected to any active Dataflows - deleted.
To add a new External Destination, click on the Create Destination button in the upper-right corner of the screen. This will provide a list of currently-available External Destinations. Each will have different requirements for establishing the link - see each Destination's documentation for further information.