What do the dots mean in relative file path?

Question

I am new to programming and learning php on my own. I have two question about the following relative path of a file

$fp = fopen (\"$_SERVER[DOCUMENT_ROOT]/..         


        

Answer 1

I like to think that the two dots drop you down by one directory level, which usually refers to the parent folder. Imagine $_SERVER[DOCUMENT_ROOT] is root:

root/
  index.php   // You are here

orders/
  orders.txt  // You are reading this file