What are namespaces and how are they used? code example

Example: whar is namespace

We can think of namespace as you made a private space for your variables or 
functions so that ther cann't be any condition where you can find name 
collision of variable or function a program.
I found out a great article on tutorialspoint and would definitely suggest you 
all to go there to have a better understanding of namespaces.
https://www.tutorialspoint.com/cplusplus/cpp_namespaces.htm