title: What means "standard input" in C language?
body: <p>I was tasked with creating a test program in <code>c</code> that reads the contents of the standard input and then prints them.</p>
  
  <p>But I have a little doubt: what is exactly <code>standard input</code>? </p>
  
  <p>Is it what I type in the keyboard? Is it a file I have to read? </p>
  
  <p>Both of them?</p>
  
  <p>Thanks.</p>