title: Working of Open System Call
body: <p>I am reading about Memory Mapped Files, the souce says it is faster than traditional methods to open a file or read a file such as an open system call and read system call respectively without giving the description that how open or read system call works.</p>
  
  <p>So here's my question  <strong>how the open system call works?</strong></p>
  
  <p>As far i know it will load the file into the memory, whereas by using mapped file only their addresses will be saved in the memory and when needed the requested page may be brought into the memory.</p>
  
  <p>I expect clarification over my so far understanding.</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>My previous understanding written above is almost wrong, for coorrect explanation refer to the accepted answer by Pawel.</p>