Meaning – The term downstream, refers to the direction in which the data flows. Usually, the data flow is described in the form of a hierarchy in which the server takes the top spot and the client comes down the line.
When the data moves from the server to the client, that is, from a higher level in the hierarchy to a lower level in the hierarchy, the flow of data is said to be downstream.
One process sending data primarily in the downstream direction is downloading. Now, the download speed itself will depend on the upstream speed of the server, the downstream speed of the user and the speed of the network between them.
Example of usage – “In cable TV, downstream signals are the network, movie and sports channels transmitted to the customer. However, if the cable TV provider also offers videos on demand or via pay-per-view, then there is also an upstream channel.”