What is a data stream and just a stream?

Question

C++ / C#

Please explain in simple terms what is a stream and a data stream in C? There are many designations on the Internet, but sometimes they contradict each other.

Answer 1

A stream is a sequence of commands. When a program is running on multiple threads, the instructions are executed in pseudo-parallel.
The data flow is a special abstraction that can be described as a railroad. When you write data, you send a train from one station, when you read data, you meet a train at another station. Accordingly, data streams can be combined (output to input).