Sources

A Source retrieves data from one of your Connections inside of an Audience.

For instance, a Source can be one of the following:

A Salesforce object (contacts, accounts...)
A Zendesk object (tickets)
A file inside of an SFTP (CSV file containing some contacts, JSON file containing events...)
A table/view of a database.
One of your systems sends us records through Webhooks/API calls.

Sources can be configured to retrieve data incrementally at a near-real-time interval (every day, hour, or minute).