I have just started learning Python & have come across "namespaces" concept in Python. While I got the jist of what it is, but am unable to appreciate the gravity of this concept. 
Some browsing on the net revealed that one of the reasons going against PHP is that it has no native support for namespaces.
Could someone explain how to use namespaces & how this feature makes programming better (not just in Python, as I assume namespaces in not a concept limited to a particular language). 
I am predominantly coming from Java and C programming backgrounds.
If you make a big program with someone else, you could write your own part of the program as you want. All variables in the file will be private, there will be no collisions.
When you write PHP programs, it is easy to rewrite global variables by mistake. In python you can import other modules variables if you want, and they will be "global" on your module.
You could think one file one object in Python. When you write PHP programs you can achieve the same by writing classes with instance variables.
What are Python namespaces all about