In Linux and other UNIX-like operating systems, each process has a standard input (*stdin*) and a standard output (*stdout*). The usual situation is that _stdin_ is your keyboard and _stdout_ is your screen or terminal window.

So when you run *find*, it will throw it's output to _stdout_. If you do nothing else, it will go to your screen or terminal window, and you will view it.

if we do this:

[source,bash]
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find /usr -name "*.h" | grep "md5"
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the "*pipe*" connects the _stdout_ of one command to the _stdin_ of another.