Consider a data stream to be an individual data source. Each source of data is separated as a stream where you can see the last time we received data from the connection as well as a sample of the raw data from every key we’ve received from it. You can also see, at the field level, the first and last time data has been seen, how many times it has been seen, and how many unique values each field has. Some integrations can have multiple data streams. For example, most of our email integrations will create a user stream for subscriber level fact data and an additional stream for behavioral event data that the user generates like opens and clicks.
You can view data streams in your account here.